JPWO2007114126A1 - Noise reduction circuit and method - Google Patents

Abstract

In the noise reduction circuit, the transistor circuit (21) receives power supply from the DC voltage source (Vcc) through the power supply line circuit (24), amplifies the input signal, and outputs an output signal. The cancellation signal adding circuit (25) acquires and attenuates a part of the output signal, thereby causing the cancellation signal to have a substantially opposite phase and substantially the same amplitude as the leakage signal leaking to the power line circuit (24). , And adding the cancellation signal to the leakage signal substantially cancels the leakage signal.

Description

  The present invention relates to a noise reduction circuit and method used for a wireless communication device such as a mobile phone and a wireless communication terminal, and a signal amplifier and a wireless communication device each using the noise reduction circuit.

  2. Description of the Related Art In electronic devices such as mobile phones, circuits that realize various functions with AC signals while supplying power with a DC power supply are used for general purposes. In such a circuit, on the premise that the reference potential of a specific part is constant, signal transmission or amplification is performed by applying an AC signal to the reference potential. Therefore, when unexpected noise is superimposed on the reference potential, the operation of the circuit becomes unstable. As described above, as a method for suppressing the fluctuation of the reference potential, it is known that a normal phase output and a reverse phase output are generated by an operational amplifier, and both are superimposed on the reference potential (for example, Patent Documents). 1).

  Further, a semiconductor integrated circuit device that can reduce crosstalk due to induction without disposing a large number of extra circuit elements has been disclosed (for example, see Patent Document 2). In the semiconductor integrated circuit device, the signal flow directions are mutually in part of the signal path such that the active path element such as an inverter that reverses the actual signal is not used and the signal path is folded in parallel and paralleled. A plurality of parallel wiring portions that are in opposite directions are formed. An inverter is not interposed in the middle of each parallel wiring portion, and that portion is a part of the actual wiring, and no extra circuit elements are required. When a signal is transmitted from one of the parallel wiring portions, the signal is turned back halfway, and the signal transmission direction is reversed. If the direction of the current flowing between the parallel conductors is reversed, the magnetic field in the opposite direction is canceled due to the electromagnetic property, and the generation of electromagnetic waves is suppressed. The parallel wiring portion can alleviate and further suppress crosstalk to other wiring in the vicinity.

JP-A-59-107615. JP 2003-158238 A.

  In recent electronic devices, such as cellular phones, which have been reduced in size and power consumption, the influence of even a very weak leak signal cannot be ignored. That is, in a small electronic device, since the mounting density on the internal substrate is high, the influence of a weak leak signal is relatively large as compared with a circuit mounted at a low density. Further, as the power consumption is reduced, the applied voltage of the DC voltage source is lowered and the reference potential with respect to the ground is also lowered, so that the influence of the weak leakage signal on the reference potential is relatively increased.

  In particular, in a wireless communication device such as a mobile phone, a transmission signal is amplified to an electric power necessary for wireless communication by an amplifier circuit in an extremely small casing, but the output signal of the amplifier circuit is the largest in the casing. There is a concern that the output signal is an interference signal for other devices and circuits when the output signal leaks to the power line circuit.

  In the above-mentioned Patent Document 1, fluctuations in the reference potential can be suppressed. However, in the recent electronic devices whose power consumption has been reduced because the reverse phase output of the operational amplifier is used to suppress the fluctuations. Is impossible to adopt. In addition, many components such as components for configuring operational amplifiers, components for adjusting the amplification factor, and output potential are required, and it is impossible to adopt them in recent electronic devices that are becoming smaller in size. It is.

  Further, assuming that the method of Patent Document 1 is applied, the inverting amplifier requires an inverting amplifier with high linearity that does not affect the signal amplified in the previous stage of the inverting amplifier, and is extremely weak. Adding to the circuit for the purpose of canceling the signal is impractical. Further, when attention is paid to a signal leaking to the power line circuit of the amplifier, in the above-mentioned Patent Document 1, a power line circuit is necessary for the inverting amplifier. The power line circuit of the amplifier becomes a noise source. As described above, the weak leakage signal cannot be suppressed as in the above-mentioned publication.

  The object of the present invention is to solve the above problems and to use a noise reduction circuit and method capable of reducing noise with a simple configuration without impairing downsizing and low power consumption, and the above-described noise reduction circuit. An object of the present invention is to provide a signal amplifier and a wireless communication apparatus.

A noise reduction circuit according to a first invention is
A signal amplifying unit that receives power supply from a power source via a power line circuit, amplifies an input signal, and outputs an output signal;
By acquiring and attenuating a part of the output signal from the signal amplifying means, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal Is added to the leaked signal to provide a signal adding means for substantially canceling the leaked signal.

  In the noise reduction circuit, the signal adding means is a passive circuit composed of a plurality of passive elements.

  Further, in the noise reduction circuit, the signal adding means uses a coupler composed of a pair of transmission lines arranged close to each other so as to be electromagnetically coupled to each other, and the cancellation signal is applied to the leakage signal. And adding.

Furthermore, in the noise reduction circuit, the power line circuit is
At the frequency of the leakage signal, a low impedance part that substantially short-circuits the leakage signal, and
A connection point between the low-impedance part and the signal amplifying means, and a high-impedance part that makes the connection point substantially open at the frequency of the leakage signal,
The signal adding means adds the leakage signal to the leakage signal at a position closer to the power source than the low impedance portion.

Here, the high impedance portion is a transmission line having a length of ¼ wavelength of the leakage signal,
The low impedance portion is a capacitor that allows a signal having a frequency of the leakage signal to pass therethrough.

  Furthermore, in the noise reduction circuit, the signal adding means is formed on a substrate on which the signal amplifying means is mounted.

A signal amplifier according to a second invention is a signal amplifier including the noise reduction circuit,
A power supply terminal connected to the power supply line circuit;
And an output terminal for outputting the output signal.

A wireless communication device according to a third invention is a wireless communication device including the noise reduction circuit,
A transmission means for transmitting the signal amplified by the signal amplification means is provided.

A wireless communication device according to a fourth aspect of the present invention is a wireless communication device comprising a receiving means for receiving a wireless signal having a predetermined frequency.
A noise reduction circuit according to claim 4 or 5,
The input signal is a square wave signal,
The power line circuit attenuates a leakage signal that is a part of the frequency component of the rectangular wave signal at a frequency of a radio signal used in the radio communication apparatus or an intermediate frequency or a frequency of a baseband signal related thereto. Features.

The noise reduction method according to the fourth invention is:
Receiving power from a power source via a power line circuit, amplifying an input signal and outputting an output signal;
By acquiring and attenuating a part of the output signal, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal is converted into the leakage signal. And substantially canceling out the leaked signal by adding together.

  According to the noise reduction circuit and method of the present invention, power is supplied from a power source through a power line circuit, an input signal is amplified and an output signal is output, and a part of the output signal is acquired and attenuated. To generate a canceling signal having substantially opposite phase and substantially the same amplitude as the leaking signal leaking into the power line circuit, and adding the canceling signal to the leaking signal, Substantially offset. As a result, noise can be significantly and effectively reduced with a simple configuration without impairing downsizing and low power consumption.

It is a block diagram which shows the structure of the radio | wireless communication circuit of the mobile telephone which concerns on the 1st Embodiment of this invention. FIG. 2 is a block diagram showing a detailed configuration of a noise reduction circuit 18 in FIG. 1. It is a block diagram which shows the detailed structure of the noise reduction circuit 18a which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the detailed structure of the noise reduction circuit 18b which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the detailed structure of the noise reduction circuit 18c which concerns on the 4th Embodiment of this invention. FIG. 5 is a circuit diagram illustrating a detailed configuration of an example of the phase adjustment transmission lines 28c and 29d in FIG. 4. 5 is a plan view showing a first application example when the noise reduction circuit 18c of FIG. 4 is applied to a printed wiring board 120. FIG. 6 is a plan view showing a second application example when the noise reduction circuit 18c of FIG. 4 is applied to a signal amplifier integrated circuit (hereinafter referred to as a signal amplifier IC) 125. FIG. FIG. 8 is a longitudinal sectional view showing the embodiment of FIG. 7 when the coupler 28A of FIG. 4 is applied to a printed wiring board 120. FIG. 6 is a longitudinal sectional view showing a first modification when the coupler 28A of FIG. 4 is applied to a printed wiring board 120; FIG. 6 is a longitudinal sectional view showing a second modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 120. FIG. 10 is a longitudinal sectional view showing a third modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 120. FIG. 3 is a diagram illustrating a time waveform of a rectangular-wave clock signal that is an input signal of the noise reduction circuit 18 of FIG. 2. It is a figure which shows the frequency characteristic of the frequency component of the clock signal of the rectangular wave of FIG. 6 is a circuit diagram of a simulation circuit substantially corresponding to the noise reduction circuit 18c of FIG. 5 used in the simulation by the present inventors. FIG. FIG. 16 is a waveform diagram showing the time waveform of the bias voltage when the presence or absence of a noise reduction circuit for confirming the noise reduction effect is shown in the simulation result of FIG. It is a graph which shows the frequency characteristic of the relative electric power of the passage coefficient in the transmission lines for phase adjustment 28c and 29d of FIG. It is a graph which shows the frequency characteristic of the phase of the passage coefficient in the transmission lines for phase adjustment 28c and 29d of FIG.

Explanation of symbols

10 ... mobile phone,
11 ... Antenna,
12 ... circulator,
13: Wireless receiver circuit,
14 ... baseband signal processing circuit 15 ... wireless transmission circuit,
16 ... modulation circuit,
17 ... driver circuit,
18 ... Noise reduction circuit,
21 ... transistor circuit,
22, 23 ... impedance matching circuit,
24 ... Power line circuit 24a ... Bypass capacitor,
24b ... transmission line,
25, 26 ... canceling signal adding circuit,
25a, 25b, 26a, 26b ... couplers,
25c, 26c ... signal lines,
27. Capacitor,
28, 29 ... canceling signal adding circuit,
28A, 29A, 29B ... couplers,
28a, 28b, 28c, 28d, 29a, 29b, 29c, 29d, 29e ... transmission line,
28as, 28bs ... strip conductors,
70: Transmission level detection circuit,
80 ... through-hole conductor,
110 ... printed wiring board,
110A ... Semiconductor substrate,
111 ... Grounding conductor,
112 ... dielectric layer,
121, 122, 123, 124 ... strip conductors,
121A, 122A, 123A, 124A ... microstrip line,
125... Signal amplifier IC,
125a ... power supply terminal,
125b ... signal output terminal,
126, 127: capacitors.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same component.

First embodiment.
FIG. 1 is a block diagram showing a configuration of a wireless communication circuit of a mobile phone according to the first embodiment of the present invention. FIG. 1 mainly shows a circuit related to transmission / reception of a radio signal. A mobile phone 10 includes an antenna 11, a circulator 12, a radio reception circuit 13, and a baseband signal processing circuit 14 for transmitting / receiving a radio signal. And a wireless transmission circuit 15. In the mobile phone 10, at the time of reception, a radio signal received via the antenna 11 is input to the radio reception circuit 13 via the circulator 13, and the radio reception circuit 13 performs a low frequency response to the received radio signal. Processing such as conversion and demodulation processing is executed, and the demodulated baseband signal is output to the baseband signal processing circuit 14. Based on the input demodulated signal, the baseband signal processing circuit 14 performs audio output, data processing, and the like.

  The wireless transmission circuit 100 includes a modulation circuit 16, a driver circuit 17, and a noise reduction circuit 18, and these circuits 16, 17, and 18 are driven by a DC voltage Vcc of a DC voltage source. In the mobile phone 10, the baseband signal processed by the baseband signal processing circuit 14 is input to the wireless transmission circuit 100 during transmission. The modulation circuit 16 in the radio transmission circuit 100 generates a modulated radio signal by modulating a predetermined carrier wave signal according to the input baseband signal, and causes the driver circuit 17, the noise reduction circuit 18, and the circulator 12. Via the antenna 11 and transmitted from the antenna 11.

  As shown in FIG. 2, the noise reduction circuit 18 includes a transistor circuit 21 that functions as a power amplifier, and a cancellation signal addition circuit 25 that reduces noise. The latter cancellation signal addition circuit 25 is connected to the transistor circuit 21 from the transistor circuit 21. Acquire and attenuate part of the output signal. At this time, a cancellation signal having substantially opposite phase and substantially the same amplitude is generated for the output signal leaking to the power supply line circuit of the transistor circuit 21, and the cancellation signal is applied to the output signal leaking to the power supply line circuit. to add. Therefore, noise leaking from the noise reduction circuit 18 to the DC voltage source side can be suppressed.

  FIG. 2 is a block diagram showing a detailed configuration of the noise reduction circuit 18 of FIG. In FIG. 2, the noise reduction circuit 18 includes a transistor circuit 21, impedance matching circuits 22 and 23, a power supply line circuit 24, and a cancellation signal addition circuit 25. In this example, the power supply line circuit 24 includes a bypass capacitor 24a and a transmission line 24b. Further, the power supply line circuit 24 extends on the side opposite to the transistor circuit 21 as viewed from the bypass capacitor 24a, and is connected to the DC voltage source Vcc via the coupler 25b of the cancellation signal adding circuit 25.

  The transistor circuit 21 is an amplifier circuit that inputs and amplifies the radio signal output from the driver circuit 17, and the amplified transmission radio signal S becomes a transmission radio signal transmitted from the antenna 11. On the input side of the transistor circuit 21, an impedance matching circuit 22 is provided for suppressing the loss of the radio signal from the driver circuit 17 by matching the output impedance of the driver circuit 17 and the input impedance of the transistor circuit 21. On the output side of the transistor circuit 21, the output impedance of the transistor circuit 21 and the output impedance when the antenna 11 is viewed through the coupler 25a are matched to suppress the loss of the radio signal to be transmitted. An impedance matching circuit 23 is provided. The transistor circuit 21 and the impedance matching circuits 22 and 23 are configured to perform amplification and matching set in advance in the frequency band of the transmission radio signal S of the transistor circuit 21.

  Further, a power line circuit 24 is connected to the transistor circuit 21, and power is supplied to the transistor circuit 21 from the DC voltage source Vcc via the power line circuit 24. In the power line circuit 24, a transmission line 24b and a bypass capacitor 24a are connected between the transistor circuit 21 and the DC voltage source Vcc in order to suppress a leakage signal from the transistor circuit 21. Here, one end of the bypass capacitor 24a is connected to the output terminal of the transistor circuit 21, while the other end of the bypass capacitor 24a is connected to a ground conductor (for example, a ground conductor 111 in FIG. 9 described later). The signal in the frequency band of the transmission radio signal S is substantially short-circuited to the ground potential. Thereby, the bypass capacitor 24a forms a low impedance portion having a relatively low impedance with respect to the frequency band.

  The phase adjusting transmission line 24b is set between the bypass capacitor 24a and the transistor circuit 21 so as to be a 1/4 wavelength transmission line with respect to the signal in the frequency band of the transmission radio signal S. Yes. Therefore, the power supply line circuit 24 is substantially open with respect to the signal in the frequency band of the transmission radio signal S, and forms a high impedance portion having a relatively high impedance. For this reason, most of the transmission radio signal S of the transistor circuit 21 is transmitted to the impedance matching circuit 23, and a part thereof is transmitted to the power supply line circuit 24 side as the leakage signal N '.

  Although most of the leakage signal N ′ flows to the ground conductor due to the action of the bypass capacitor 24 a, a part of the leakage signal N ′ is transmitted to the DC voltage source Vcc by the power line circuit 24. Therefore, if no countermeasure is taken, an output signal (hereinafter referred to as a leakage signal N) leaking from the transmission line 24b to the DC voltage source Vcc side can be generated. However, in the mobile phone 10 as in the present embodiment, since miniaturization and low power consumption are progressing, even if the leakage signal N is weak, it cannot be ignored.

  Therefore, in the present embodiment, the canceling signal adding circuit 25 cancels the leakage signal N using a part of the transmission radio signal S as shown below. The cancellation signal adding circuit 25 is a passive circuit configured by including couplers 25a and 25b and a signal line 25c. In FIG. 2, the coupler 25a is configured to include a transmission line between the impedance matching circuit 23 and the antenna 11, and another transmission line disposed in close proximity so as to be electromagnetically coupled thereto. Then, a part of the transmission radio signal S output from the impedance matching circuit 23 is acquired and output to the coupler 25b via the signal line 25c.

  The coupler 25b includes a transmission line provided between the bypass capacitor 24a and the DC voltage source Vcc, and another transmission line disposed close to the electromagnetic wave so as to be electromagnetically coupled thereto. Composed. Here, with respect to the leakage signal N input from the power line circuit 24 to the coupler 25b, a part of the transmission radio signal S input from the coupler 25a to the coupler 25b via the signal line 25c is substantially omitted. The line length and characteristic impedance of the power supply line circuit 24 and the line length and characteristic impedance of the signal line 25c of the impedance matching circuit 23 and the cancellation signal adding circuit 25 are adjusted in advance so as to have the opposite phase and substantially the same amplitude. . Therefore, the coupler 25b of the cancellation signal adding circuit 25 adds a part of the transmission radio signal S acquired by the coupler 25a to the leakage signal N input from the power line circuit 24 to the coupler 25b. Thus, the leakage signal N is suppressed and is not transmitted to the DC voltage source Vcc side.

  In the present embodiment, since the signal of the signal source of the leakage signal N is the transmission wireless signal S, the frequency band of the transmission wireless signal S and the leakage signal N is the same band. Further, when the transmission radio signal S having a certain frequency is output, the frequency of the leakage signal N is substantially the same. Therefore, as in this embodiment, the canceling signal adding circuit 25, which is a passive circuit capable of adjusting the phase and amplitude, is configured to easily add a signal for canceling the leakage signal N to the power line circuit 24. Can do.

  Further, the transmission radio signal S is a signal after being amplified by the transistor circuit 21, and the leakage signal N is a signal obtained by further attenuating the leakage signal N ′ leaked to the power line circuit 24. Therefore, the power of the leakage signal N is extremely small compared to the power of the transmission radio signal S, and the cancellation signal for canceling the leakage signal N is generated by attenuating the power of the transmission radio signal S by the cancellation signal adding circuit 25. can do. For this reason, no new power consumption such as an amplifier circuit is required to cancel the leakage signal N, and this can be realized very simply by the passive circuit.

  In this embodiment, the transmission line connected to the signal line 25c in the coupler 25b is disposed close to the electromagnetic wave so as to be electromagnetically coupled to the transmission line between the bypass capacitor 24a and the DC voltage source Vcc. Therefore, the leakage signal N can be canceled without affecting the impedance when the power supply line circuit 24 is viewed from the output terminal of the transistor circuit 21.

  For example, when the transmission line of the coupler 25b is connected to the connection point between the bypass capacitor 24a and the transmission line 24b, the impedance of the transistor circuit 21 viewed from the power line circuit 24 side changes, and the transistor circuit 21 changes to the power line circuit 24. There is a possibility that the leakage signal N ′ leaking to the terminal increases. However, in the present embodiment, a coupler 25b is connected between the bypass capacitor 24a and the DC voltage source Vcc, and a power line circuit 24 including the bypass capacitor 24a and a transmission line 24b having a 1/4 wavelength line length. Thus, the leakage signal N can be further canceled while maintaining a mechanism for suppressing leakage of the leakage signal N to the power line circuit 24.

  Further, by connecting the coupler 25b between the bypass capacitor 24a and the DC voltage source Vcc, the cancellation signal adding circuit 25 can be coupled without considering the impedance when the transistor circuit 21 side is viewed from the bypass capacitor 24a. The configuration of the devices 25b, 25a, etc. can be determined. That is, in the canceling signal adding circuit 25, it is possible to determine the circuit configuration by paying attention only to the phase and amplitude of the leakage signal N, and the canceling signal adding circuit 25 can be designed with a very high degree of freedom. It is.

  As described above, the configuration that can be designed with a high degree of freedom is particularly important in the mobile phone 10 that is being miniaturized. That is, since the substrate and the like in the mobile phone 10 are small, it is not easy to change the arrangement and the like after determining components other than the cancellation signal adding circuit 25. However, if the design flexibility of the cancellation signal addition circuit 25 is high, it is easy to configure the cancellation signal addition circuit 25 without changing any components other than the cancellation signal addition circuit 25. Therefore, the present invention can be easily applied even to a small electronic device.

Second embodiment.
In the embodiment according to the present invention, it is only necessary to generate and add a signal that cancels noise by acquiring and attenuating a part of the transmission radio signal S after amplification. Also, various configurations can be adopted. FIG. 3 is a block diagram showing a detailed configuration of the noise reduction circuit 18a according to the second embodiment of the present invention. The noise reduction circuit 18a of FIG. 3 is characterized in that a cancellation signal addition circuit 26 is provided instead of the cancellation signal addition circuit 25 of FIG. 2 as compared with the noise reduction circuit 18 of FIG. In FIG. 3, the canceling signal adding circuit 26 includes a capacitor 27, couplers 26a and 26b, and a signal line 26c. That is, a configuration is adopted in which a part of the transmission radio signal S is acquired using a coupler 26 a including a transmission line to the transmission level detection circuit 70. Hereinafter, only the differences of FIG. 2 will be described in detail with respect to the configuration of FIG.

  In FIG. 3, the output terminal of the impedance matching circuit 23 is connected to the transmission level detection circuit 70 via the capacitor 27 and the coupler 26a, and a part of the transmission radio signal S output from the impedance matching circuit 23 is detected in the transmission level. The signal is supplied to the detector in the circuit 70 and used for detecting the level of the transmission radio signal S.

  Therefore, in the present embodiment, the cancellation signal adding circuit 26 is configured by a passive circuit. The coupler 26a of the canceling signal adding circuit 26 includes a transmission line between the capacitor 27 and the transmission level detection circuit 70, and a transmission line arranged in close proximity so as to be electromagnetically coupled thereto. The transmission line is connected to the coupler 26b via the signal line 26c. Therefore, a part of the transmission radio signal S transmitted from the capacitor 27 to the transmission level detection circuit 70 is acquired by the coupler 26a and then transmitted to the coupler 26b via the signal line 26c.

  Further, the coupler 26b of the cancellation signal adding circuit 26 includes a transmission line between the bypass capacitor 24a and the DC voltage source Vcc, and a transmission line arranged in close proximity so as to be electromagnetically coupled thereto. The coupler 26b cancels out the leaked signal N by adding a part of the transmission radio signal S acquired by the coupler 26a to the leaked signal N. That is, a part of the transmission radio signal S input from the coupler 26a to the coupler 26b via the signal line 26c is substantially opposite to the leakage signal N input from the power line circuit 24 to the coupler 26b. The line length and characteristic impedance of the power supply line circuit 24 and the line lengths and characteristic impedances of the impedance matching circuit 23, the coupler 26a, and the signal line 26c are adjusted in advance so that the phase and the amplitude are approximately the same. Therefore, the coupler 26b of the cancellation signal adding circuit 26 adds a part of the transmission radio signal S acquired by the coupler 26a to the leakage signal N input from the power line circuit 24 to the coupler 26b. Thus, the leakage signal N is suppressed and is not transmitted to the DC voltage source Vcc side.

  Also in the present embodiment, a canceling signal can be easily added to the leakage signal N by the canceling signal adding circuit 26 that is a passive circuit, as in the above-described embodiment. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit.

  Further, while maintaining a mechanism for suppressing the power that the transmission radio signal S leaks to the power supply line circuit 24 by the power supply line circuit 24 including the capacitor 24a and the quarter wavelength transmission line 24b, the power that further cancels the leakage signal N. Can be supplied. With this configuration, the cancellation signal adding circuit 26 can be designed with a very high degree of freedom. In addition, due to the high degree of design freedom of the cancellation signal addition circuit, it is possible to configure the cancellation signal addition circuit with various circuits, and various configurations shown in FIGS. 2 and 3 can be adopted. It becomes possible.

Third embodiment.
FIG. 4 is a block diagram showing a detailed configuration of a noise reduction circuit 18b according to the third embodiment of the present invention. The noise reduction circuit 18b of FIG. 4 is characterized in that it includes a cancellation signal addition circuit 28 instead of the cancellation signal addition circuit 25, as compared with the noise reduction circuit 18 of FIG. In the present embodiment, the cancellation signal adding circuit 28 includes transmission lines 28a, 28b, 28c, and 28d, the transmission lines 28c and 28b between the bypass capacitor 24a and the DC voltage source Vcc, and the impedance matching circuit 23. The attenuation and the phase of the transmission radio signal S are adjusted by changing the line length of the transmission lines 28a and 28d between the antenna 11 and the distance between the wires (preferably, further the characteristic impedance).

  In FIG. 4, the connection point between the transmission line 24b and the capacitor 24a is connected to the DC voltage source Vcc via the transmission line 28c and the transmission line 28b, while the output terminal of the impedance matching circuit 23 is connected to the transmission line 28d and the transmission line 28c. It is connected to the output terminal T2 to the antenna 11 through the line 28a. Here, the coupler 28A is configured to include a pair of transmission lines 28a and 28b that are arranged close to each other so as to be electromagnetically coupled to each other, and the attenuation amount of the transmission signal S mainly depending on the distance between the wires and the parallel length. Is adjusted. The transmission line 28c is a phase adjustment transmission line, and the line length and characteristic impedance of the transmission line 28c are adjusted so as to cancel each other. That is, in the present embodiment, the impedance matching circuit 23 is provided without using an independent circuit for acquiring a part of the transmission radio signal S using the transmission lines 28a and 28d between the impedance matching circuit 23 and the antenna 11. The canceling signal adding circuit 28 is configured together with the transmission lines 28b and 28c.

  In the cancellation signal adding circuit 28 configured as described above, the leakage signal N is canceled with a part of the transmission radio signal S and is not transmitted to the DC voltage source Vcc side. Similarly to the above-described embodiment, a signal that cancels the leakage signal N can be easily added to the transmission line 28b on the power line circuit 24 side by the passive circuit. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit. Furthermore, the power for canceling the leakage signal N using a part of the transmission radio signal S while maintaining a mechanism for suppressing the power of the leakage signal N that the transmission radio signal S leaks to the power supply line circuit 24 by the power supply line circuit 24. Can be supplied. With this configuration, the cancellation signal adding circuit 28 can be designed with a very high degree of freedom.

Fourth embodiment.
FIG. 5 is a block diagram showing a detailed configuration of a noise reduction circuit 18c according to the fourth embodiment of the present invention. The noise reduction circuit 18c of FIG. 5 is characterized in that a cancellation signal addition circuit 29 is provided in place of the cancellation signal addition circuit 25 of FIG. 1 as compared with the noise reduction circuit 18 of FIG. In the present embodiment, the canceling signal adding circuit 29 includes a coupler 29A including a pair of transmission lines 29a and 29c arranged close to each other so as to be electromagnetically coupled to each other, and a phase adjustment transmission line 29d. And a coupler 29B composed of a pair of transmission lines 29b and 29e arranged close to each other so as to be electromagnetically coupled to each other, and a transmission line between the bypass capacitor 24a and the DC voltage source Vcc. 29b, the transmission line 29a between the impedance matching circuit 23 and the antenna 11, and the line lengths of the transmission lines 29c, 29d, and 29e formed between them, and the inter-wiring distances (preferably more characteristic impedance) By adjusting, the attenuation and phase of the transmission radio signal S are adjusted.

  In FIG. 5, a part of the transmission radio signal S is acquired by the transmission line 29c of the coupler 29A, and the part of the signal is transmitted to the transmission line 29e of the coupler 29B via the phase adjustment transmission line 29d. By adjusting the phase and amplitude, the leakage signal N transmitted through the transmission line 29b connected to the power line circuit 24 is canceled by a part of the acquired transmission radio signal S, and the DC voltage source Vcc side Will not be transmitted.

  Also in this embodiment, a signal that easily cancels the leakage signal N by the passive circuit can be added to the leakage signal N flowing through the power line circuit 24, as in the above-described embodiment. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit. Furthermore, the power that cancels the leakage signal N while maintaining a mechanism that suppresses the power that the transmission radio signal S leaks to the power line circuit 24 by the power line circuit 24 that includes the bypass capacitor 24a and the quarter-wave transmission line 24b. Can be supplied. Further, with this configuration, the cancellation signal adding circuit 29 can be designed with a very high degree of freedom.

  FIG. 6 is a circuit diagram showing a detailed configuration of an example of the phase adjustment transmission lines 28c and 29d of FIG. For example, as shown in FIG. 6, the phase adjustment transmission lines 28c and 29d are L-type circuits including a capacitor C1 and an inductor L1, and include phase shift amounts by adjusting respective values of the capacitor C1 and the inductor L1. The line length, amplitude and characteristic impedance can be adjusted. The simulation results of the electrical characteristics of the phase adjustment transmission lines 28c and 29d will be described later in detail. Further, the transmission line 29d may be a series circuit of a capacitor C1 and an inductor L1, or a circuit including a resistor.

Application example to printed circuit board.
As described above, each embodiment according to the present invention can be realized by the various circuits as described above, and the cancellation signal adding circuit 26-29 is provided on the printed wiring board (dielectric board) 110 on which the signal amplifier IC 125 is mounted. It may be realized by the above, or may be realized inside the signal amplifier IC 125, and various modes can be adopted, which will be described in detail below.

  FIG. 7 is a plan view showing a first application example when the noise reduction circuit 18 c of FIG. 4 is applied to the printed wiring board 120. That is, FIG. 7 is a diagram illustrating the signal amplifier IC 125 mounted on the printed wiring board 110 and its peripheral circuits. In FIG. 67, the signal amplifier IC 125 is connected to the power supply terminal 125a and the output terminal 125b. The strip conductors 121 and 122 on the printed wiring board 110 are shown. Here, the strip conductor 121 and the ground conductor 111 (see FIG. 9) formed on the back surface of the printed wiring board 110 constitute a microstrip line 121A, and the strip conductor 122 and the printed wiring board 110 are formed on the back surface. The ground strip 111 (see FIG. 9) constitutes a microstrip line 122A.

  The signal amplifier IC 125 shown in FIG. 7 is a circuit component that incorporates the impedance matching circuits 22 and 23 and the transistor circuit 21 in the noise reduction circuit 18 shown in FIG. 4, and the power supply terminal 125 a has the transistor circuit 21, the impedance matching circuit 23, and the like. The output terminal 125 b is connected to the output side of the impedance matching circuit 23. Therefore, in FIG. 7, the strip conductor 121 includes the transmission line 24 b of the power supply line circuit 24 in FIG. 4, and the strip conductor 122 corresponds to the line conductor between the antenna 11 and the impedance matching circuit 23. A bypass capacitor 24a is connected to a part of the strip conductor 121. The strip conductor 121 between the bypass capacitor 24a and the output terminal of the transistor circuit 21, the wiring conductor in the signal amplifier IC 125, and the power supply terminal 125a correspond to the transmission line 24b. To do. The other end of the bypass capacitor 24a is connected to the ground conductor 111 through a through-hole conductor 80 filled in a through-hole penetrating the printed wiring board 110 in the thickness direction and grounded. Therefore, in the first application example shown in FIG. 7, the strip conductor 122 connected to the output terminal 125 b is adjusted to the line length, shape, etc., and the part is electromagnetically coupled to the strip conductor 121. By arranging the coupler 28A in the vicinity, the leakage signal N transmitted on the strip conductor 121 by the coupler 28A is canceled by a part of the transmission radio signal S transmitted on the strip conductor 122. To do.

  According to the first application example configured as described above, in the printed wiring board 110 on which the arbitrary signal amplifier IC 125 is mounted, the leakage signal N leaking from the signal amplifier IC 125 to the power supply line circuit 24 cannot be ignored. Even if it exists, the said leak signal N can be canceled easily.

  FIG. 8 is a plan view showing a second application example when the noise reduction circuit 18c of FIG. 4 is applied to the signal amplifier IC125. As shown in FIG. 8, it is also possible to cancel the leakage signal N in the signal amplifier IC 125 so that noise does not leak from the signal amplifier IC 125. That is, the signal amplifier IC 125 includes a power supply terminal 125a and an output terminal 125b. The signal amplifier IC 125 includes the impedance matching circuits 22 and 23, the transistor circuit 21, the bypass capacitor 24a, and the transmission line shown in the noise reduction circuit 18 of FIG. Circuits corresponding to 24b and the cancellation signal adding circuit 25 are incorporated.

  On the semiconductor substrate of the signal amplifier IC 125 of FIG. 8, a strip conductor 123 including the transmission line 24b and the transmission line of the coupler 28A is formed between the transistor circuit 21 and the power supply terminal 125a, and the transistor circuit 21 and the output terminal 125b. The strip conductor 124 including the impedance matching circuit 23 and the transmission line of the coupler 28A is formed between the two. Here, the strip conductor 123 and a ground conductor (not shown, corresponding to the ground conductor 110 in FIG. 9) formed on the back surface of the semiconductor substrate 110 </ b> A constitute a microstrip line 123 </ b> A, The microstrip line 124A is constituted by a ground conductor (not shown, corresponding to the ground conductor 110 in FIG. 9 and the like) formed on the back surface of the semiconductor substrate 110A. One end of the bypass capacitor 24a is connected to a part of the strip conductor 123, and the other end is connected to the ground conductor via a through-hole conductor 80 filled in a through-hole penetrating the semiconductor substrate 110A in the thickness direction. Grounded. The impedance matching circuit 23 includes a part of the strip conductor 124 and capacitors 126 and 127 each having one end grounded via the through-hole conductor 80. Here, the cancellation signal addition is performed by the impedance matching circuit 23, the strip conductor 124, the strip conductor 123, and the coupler 28A that is disposed close to each other so that the two strip conductors 123 and 124 are electromagnetically coupled to each other. A circuit 28 is configured.

  In FIG. 8, the impedance matching circuit 22 is not shown. Here, by adjusting the line length, shape, and the like of the strip conductor 124, the leakage signal N is substantially canceled by adding a part of the transmission radio signal S to the leakage signal N by the coupler 28A. According to the above configuration, the leakage signal N can be prevented from leaking to the external circuit from the power supply terminal 125a of the signal amplifier IC125.

  Further, the noise reduction circuit according to the present invention may be configured by elements different from the circuit elements described in the above embodiments. For example, although the transmission line 24b described above may be configured by the strip conductors 121 and 122, the frequency of the transmission radio signal S can be increased by connecting a circuit including a choke coil and a bypass capacitor to the output terminal of the transistor circuit 21. Alternatively, a circuit having a high impedance may be configured. Further, the passive circuit described above can be constituted by various circuit elements other than the wiring pattern such as the strip conductors 121-124, and a combination of various elements such as a coil, a capacitor, and a resistor can be adopted.

  7 and 8, the signal amplifier IC 125 is used. However, the present invention is not limited to this. The signal amplifier is not formed in the IC, and the signal amplifier is configured using a field effect transistor. May be.

  Further, in the above-described example, the power line circuit 24 and the cancellation signal adding circuit 25 are described in the same layer on the printed wiring board 110 or the semiconductor substrate 110A. However, these circuits are formed in different layers. May be. That is, the canceling signal adding circuit 25 can transmit power from the strip conductor 121 or 123 between the impedance matching circuit 23 and the antenna 11 to the wiring such as the strip conductor between the bypass capacitor 24a and the DC voltage source Vcc. As long as possible, the power supply line circuit 24 and the cancellation signal adding circuit 25 may be formed in different layers, and various configurations can be employed. Of course, any one or both of the power supply line circuit 24 and the cancellation signal adding circuit 25 may be formed in a plurality of layers via the through-hole conductor 80. In particular, an embodiment of the coupler 28A will be described in detail below.

  9 is a longitudinal sectional view showing the embodiment of FIG. 7 when the coupler 28A of FIG. 4 is applied to the printed wiring board 120. As shown in FIG. In FIG. 9, the strip conductors 28as and 28bs of a pair of transmission lines of the coupler 28A are juxtaposed in close proximity to each other on a printed wiring board 110 having a ground conductor 111 formed on the back surface. Has been. The coupler 28A is configured by the above configuration.

  FIG. 10 is a longitudinal sectional view showing a first modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 120. As shown in FIG. In FIG. 10, a pair of transmission line strip conductors 28as and 28bs of a coupler 28A are formed close to each other on a printed wiring board 110 having a ground conductor 111 formed on the back surface thereof. However, the strip conductor 28as is formed on the front surface of the printed wiring board 110, the dielectric layer 112 is formed thereon, and the strip conductor 28bs is formed on the strip conductor 28as immediately above the strip conductor 28as. . The coupler 28A is configured by the above configuration.

  FIG. 11 is a longitudinal sectional view showing a second modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 120. As shown in FIG. In the second modified example of FIG. 11, the strip conductor 28bs is formed on the dielectric layer 112 at a position shifted from the position immediately above the strip conductor 28as, as compared with the first modified example of FIG. The coupler 28A is configured by the above configuration.

  FIG. 12 is a longitudinal sectional view showing a third modification when the coupler 28 </ b> A of FIG. 4 is applied to the printed wiring board 120. The third modification of FIG. 12 is formed so that the pair of strip conductors 28as and 28bs of the coupler 28A are orthogonal to each other as compared with the first modification of FIG. The coupler 28A is configured by the above configuration.

  Although the two-layer structure is shown in the examples of FIGS. 9 to 12, the present invention is not limited to this, and the structure may be formed of strip conductors 28as and 28bs in arbitrary layers with a structure of three or more layers. Further, the pair of strip conductors 28as and 28bs need not be parallel to each other and may not have the same line width.

  Further, the case where the input signal to the noise reduction circuit 18 in FIG. 2 is a rectangular clock signal will be discussed below. 13 is a diagram showing a time waveform of a rectangular clock signal that is an input signal of the noise reduction circuit 18 of FIG. 2, and FIG. 14 is a diagram showing frequency characteristics of frequency components of the rectangular clock signal of FIG. is there. When the input signal to the noise reduction circuit 18 of FIG. 2 is a rectangular wave clock signal as shown in FIG. 13, the clock signal includes a harmonic component and has a relatively wide frequency band as shown in FIG. In the place where the frequency band of the communication system and the harmonic component of the clock signal overlap with each other, the frequency band of the radio signal and the low frequency are compared with the circuit of the communication system (particularly the receiving circuit). In the frequency band related to the frequency band of the radio signal, such as the frequency band of the intermediate frequency signal after conversion and the frequency band of the baseband signal, there is a possibility that an influence such as interference may occur. In particular, when the reception frequency band and the harmonic component of the clock signal overlap, a minute received signal power cannot be restored correctly, and for example, a mobile phone cannot be used for communication. When a clock signal is amplified, all harmonic components leak to the bias circuit side. However, by using the noise reduction circuits 18, 18a, 18b, and 18c according to the present embodiment, only the frequency band that affects the communication system is used. (Because the power supply line circuit 24 operates as a filter circuit that removes only a predetermined frequency band or passes only another predetermined frequency band as described above), the leakage signal N can be significantly reduced. It has the following effects. In this case, for example, the transistor circuit 21 is a circuit such as a mixer provided in the wireless reception circuit 13 of the wireless communication device. Further, the application example described with reference to FIGS. 13 and 1 as described above can be applied to, for example, a digital circuit.

FIG. 15 is a circuit diagram of a simulation circuit substantially corresponding to the noise reduction circuit 18c of FIG. 5 used in the simulation by the present inventors. In FIG. 15, the simulation circuit is realized by a harmonic balance analysis method using a simulator ADS (Advanced Design System) manufactured by Agilent, and includes a reference high-frequency signal generator 30 including an internal output resistance Rr, a transmission line, and the like. 31-38, 39a, 39b, 40-43, field effect transistors TR1, TR2, resistors R11, R21, capacitors C11-C13, C21, inductors L11, L21, DC voltage sources 51, 52, a load And a resistor _RL . Here, a pair of transmission lines 39a and 39b constitutes a coupler 39, and a transmission line 38, a capacitor C13, and a coupler 39 constitute a cancellation signal adding circuit 60. In the simulation circuit configured as described above, the voltage waveform of the bias voltage was measured at the monitor point Tm that is the connection point of the transmission lines 42 and 43.

  FIG. 16 is a waveform diagram showing the simulation result of FIG. 15 and showing the time waveform of the bias voltage when the noise reduction circuit 60 for confirming the noise reduction effect is present. As can be seen from FIG. 16, when the noise reduction circuit 60 is not provided, the leakage signal N is superimposed on the bias voltage. However, when the noise reduction circuit 60 is provided, the leakage signal N is significantly reduced. I understand that.

  17 is a graph showing the frequency characteristics of the relative power of the pass coefficient in the phase adjustment transmission line of FIG. 6, and FIG. 18 is a graph showing the frequency characteristics of the phase of the pass coefficient in the phase adjustment transmission line of FIG. . As apparent from FIGS. 17 and 18, it is understood that the passing power can be changed according to the frequency and the phase shift amount can be changed.

Summary of embodiments of the present invention.
According to the present invention, when the output signal amplified by the signal amplifying means leaks to the power supply line circuit, a part of the output signal is attenuated, and has substantially the same phase and the same amplitude as the leaked output signal. Noise is suppressed by adding signals. That is, the noise to be suppressed is a signal in which the output signal amplified by the signal amplifier leaks to the power supply line circuit, and is a weak signal. On the other hand, the signal generated by the signal adding unit is generated from a part of the output signal after being amplified by the signal amplifying unit, and the amplified output signal is a signal having a large power.

  Therefore, the signal adding means in the present invention does not require an amplifier circuit in order to generate the signal having the substantially opposite phase and substantially the same amplitude, and can be generated by attenuating the output signal. As a result, it is possible to provide a circuit that cancels out the output signal leaking to the power line circuit without power consumption. In addition, when generating the signal having substantially the same phase and amplitude, the components for forming the amplifier circuit and the like are completely unnecessary, and the signal adding means can be realized without hindering the miniaturization of the circuit. it can.

  Here, the signal amplifying means may be any circuit that amplifies the input signal and obtains the output signal, and amplifies the input signal using the power supplied via the power line circuit. Of course, it is possible to appropriately perform impedance matching or insert a filter in each line connected to the signal amplification means.

  In the present invention, when an input signal is amplified to obtain an output signal, a signal leaking to the power line circuit is suppressed. Therefore, if a signal amplifying means that causes a signal to leak into the power supply line circuit is used as an application object of the present invention, the effect appears remarkably, and amplifying means for a high-frequency signal (for example, a signal of 30 MHz or more) An example. For this reason, the present mobile phone using the 800 MHz to 2 GHz band, the current wireless LAN using the 2 GHz and 5 GHz bands, and the like are suitable applications of the present invention.

  The signal adding means acquires a part of the output signal from the signal amplifying means. That is, in the present invention, the output signal leaked from the signal amplification means is canceled using the output signal amplified by the signal amplification means. In the signal amplification means, the former is an output signal to be acquired by amplification, and the latter is not required. In general, the former is much larger than the latter because of the noise. Therefore, in the signal adding means, it is possible to obtain a signal that can sufficiently cancel out the leaked signal only by obtaining a part of the output signal from the signal amplifying means.

  In addition, various configurations can be employed to acquire a part of the output signal, and a wiring that conducts with the wiring that transmits the output signal is not essential. That is, if the output signal is a high-frequency signal, a circuit that becomes part of the signal adding means is wired near the transmission line through which the output signal is transmitted. To leak. Therefore, a configuration may be adopted in which a part of the output signal is acquired by wiring that is not secured to the output line of the signal amplification means. According to this configuration, it is possible to generate a signal that cancels out the output signal leaking to the power supply line circuit without excessively damaging the output power of the signal amplification means.

Further, the signal adding means only needs to be able to attenuate the output signal from the signal amplifying means, and may be configured to attenuate the signal simultaneously by acquiring a part of the output signal as described above. Then, a configuration in which a part of the output signal is acquired and the signal whose power is attenuated is further attenuated may be used. Since such signal attenuation can be performed without receiving power from the power source, the attenuation can be realized with a very simple configuration.

  Further, the signal generated by the signal adding means may be a signal having substantially the same phase and amplitude as the output signal leaking to the power line circuit. That is, it is only necessary to generate a signal that cancels the output signal leaking to the power line circuit. Of course, if the output signal leaks to the power supply line circuit is exactly the opposite phase and the same amplitude, the leaking signal can be canceled out. However, if it is difficult to accurately specify the phase and amplitude of the leaking signal, it is sufficient that the signal adding means adds the signals and attenuates at least the leaking signal.

  In this sense, it is only necessary that the signal adding means can generate a signal having substantially the same phase and amplitude as the output signal leaking to the power supply line circuit. For example, a configuration may be adopted in which a signal having substantially opposite phase and substantially the same amplitude as the output signal leaking to the power supply line circuit is generated by a wiring or component that can be actually selected.

  Further, since the output signal may have a predetermined frequency band, the signal adding means has a signal having the largest amplitude in the frequency band in the output signal leaking to the power line circuit, and having the highest transmission efficiency. A configuration may be adopted in which a signal having a frequency that is most desired to be suppressed, such as a large signal, is selected, and a signal having substantially the same phase and amplitude is added to this signal.

  In the present invention, the output signal leaking to the power line circuit is a part of the signal amplified by the signal amplifying means and substantially coincides with the frequency band of the amplified signal. Therefore, by canceling the output signal leaking to the power line circuit by a part of the amplified signal, it is possible to attenuate the leak signal for all frequency bands of the output signal leaking to the power line circuit very easily. is there.

  Furthermore, the signal adding means in the present invention may be constituted by a passive circuit. That is, the passive circuit is a component of a circuit that does not have an amplifying function, such as a resistor, a capacitor, and a coil. These components transmit the signal while giving attenuation and phase fluctuation to the signal. In the present invention, a signal that attenuates a part of the output signal having a large power and leaks to the power line circuit. Therefore, this signal can be easily generated by a passive circuit. Further, since it is a passive circuit, it is not necessary to supply power from the power source when generating this signal. Furthermore, since the signal adding means can be realized by simple components, the device can be easily downsized.

  As described above, as an example of configuring the signal addition unit with a passive circuit, an example of configuring the signal addition unit with only wiring may be employed. That is, it is possible to adjust the phase and amplitude of the output signal by adjusting the length and shape of the wiring, the distance between the closely arranged wirings, the parallel wiring length, and the like. It is possible to obtain a part of the output signal from the signal and add it to the power line circuit to cancel the leaked output signal. According to this configuration, the signal adding means can be formed very easily.

  Note that the present invention may be applied to signal amplifying means adopting a configuration for suppressing an output signal leaking into the power line circuit. That is, in the power line circuit, leakage of the output signal can be suppressed by adjusting the impedance with respect to the frequency of the output signal. For example, in the power line circuit, a low impedance part whose ground is substantially short-circuited at the frequency of the leaked output signal, and a power line circuit between the low impedance part and the signal amplification means A high impedance portion that is substantially open to the frequency is formed.

  According to this configuration, an output signal leaking to the power supply line circuit can be suppressed by the high impedance portion and the low impedance portion. However, even if such a circuit is configured with actual circuit components, the leaked output signal cannot be completely set to “0”, and a part of the power leaks to the power source side. Such a leakage cannot be ignored in recent electronic devices whose size and power consumption have been reduced.

  Therefore, if the present invention is applied to the configuration in which the leakage of the output signal is suppressed by the impedance as described above in the power line circuit, the leakage of the output signal to the power line circuit can be suppressed to an extremely small level. At this time, the signal generated by the signal adding means is added to the power supply side from the low impedance portion. That is, in the power line circuit, since the leakage of the signal is prevented by the combination of the low impedance part and the high impedance part, if the signal by the signal adding means is added to the power source side from the low impedance part, the low impedance part The signal leaking from the low impedance part to the power supply side can be further suppressed while maintaining a mechanism for preventing the signal leakage by combining the low impedance part and the high impedance part.

  Note that the low impedance portion and the high impedance portion may be configured to suppress signals leaking to the power supply line circuit when they are combined. However, even if these low-impedance part and high-impedance part are configured by actual circuit components or the like, the impedance by the low-impedance part cannot be “0” and the impedance by the high-impedance part cannot be made infinite. In this sense, in the low impedance part, the signal at the frequency of the output signal is substantially short-circuited to the ground, and in the high impedance part, the signal is leaked by being substantially open to the signal at the frequency of the leaking output signal. It is sufficient if the signal can be suppressed.

  As such a configuration, for example, a low-impedance part is configured by a capacitor that passes a signal having a frequency of the leaking output signal, and the leakage signal between the low-impedance part and the signal amplification means is 1 / of the leaking output signal. The high impedance portion can be formed by a transmission line having a length of 4 wavelengths. According to this configuration, the low impedance portion and the high impedance portion can be configured by a very simple circuit.

  As described above, the signal adding means adds signals while maintaining a mechanism for preventing signal leakage by combining the low impedance portion and the high impedance portion, thereby greatly increasing the degree of design freedom in the signal adding means. can do. That is, when adopting a configuration in which a signal is added to the power line circuit of the signal amplifying unit, the impedance of the power line circuit as viewed from the signal amplifying unit generally fluctuates. Need to design.

  However, as described above, if the signal generated by the signal adding means is added to the power supply side from the low impedance portion, the power amplification side from the low impedance portion that is substantially short-circuited to the ground when viewed from the signal amplification means. Since the addition by the signal adding means is performed, the impedance viewed from the signal amplifying means hardly changes. Therefore, as long as a signal is added to the power supply side from the low impedance part, the circuit configuration in the signal adding means can be freely determined, and a design with a very high degree of freedom can be performed.

  Furthermore, although the ground is substantially short-circuited at the frequency of the leaked output signal by the low impedance unit, the signal added by the signal adding means is obtained by acquiring and attenuating a part of the output signal. Even at the frequency of the signal to be added, the ground is substantially short-circuited by the low impedance portion. Therefore, it is possible to cancel the signal without leaking the signal added by the signal adding means to the signal amplifying means side.

  Furthermore, the noise reduction device according to the present invention can be applied to various signal amplification means. For example, if the signal amplifying means is provided as one component and the component is mounted on the substrate, the signal leaking from the component can be suppressed by forming the signal adding means for the substrate. . Therefore, even when a component that leaks noise is used, the noise can be easily suppressed.

  Furthermore, it is also possible to provide a component that does not leak noise according to the present invention. As an example for that purpose, a component including a signal amplifying unit and a signal adding unit according to the present invention, and a power terminal connected to the power line circuit and an output terminal for outputting the output signal may be configured. . That is, the output signal leaking to the power line circuit is canceled inside the component, and the output signal does not leak from the power terminal. Therefore, the user of this component can supply predetermined power from the power supply terminal without considering the leakage signal and obtain an output signal from the output terminal.

  Furthermore, as an example of an application target of the present invention, a wireless communication device such as a mobile communication device can be employed. That is, in a mobile communication device, a transmission signal is obtained by a signal amplifying means, and the transmission signal often becomes large power in this device. In recent years, mobile communication devices have been reduced in size and power consumption, and there are cases where the influence of the output signal amplified by the signal amplification means cannot be ignored. Therefore, if a mobile communication device including the signal amplification means and the signal addition means of the present invention is configured, it is possible to provide a mobile communication device with a small size and low power consumption without being affected by noise.

  Although the case where the present invention is realized as an apparatus has been described above, the present invention can also be applied to a method for realizing such an apparatus. Of course, the substantial operation is the same as that of the apparatus described above. In addition, the noise reduction apparatus as described above may be realized alone, applied to a certain method, or used in a state where the method is incorporated in another device. However, the present invention is not limited to this and includes various modes.

  As described in detail above, according to the noise reduction circuit and method of the present invention, power is supplied from a power supply via a power supply line circuit, an input signal is amplified and an output signal is output, and the output signal By acquiring a part and attenuating, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal is added to the leakage signal. This substantially cancels the leakage signal. As a result, noise can be significantly and effectively reduced with a simple configuration without impairing downsizing and low power consumption. Therefore, the present invention can be widely applied to wireless communication devices such as mobile phones and GPS receivers.

  The present invention relates to a noise reduction circuit and method used for a wireless communication device such as a mobile phone and a wireless communication terminal, and a signal amplifier and a wireless communication device each using the noise reduction circuit.

  2. Description of the Related Art In electronic devices such as mobile phones, circuits that realize various functions with AC signals while supplying power with a DC power supply are used for general purposes. In such a circuit, on the premise that the reference potential of a specific part is constant, signal transmission or amplification is performed by applying an AC signal to the reference potential. Therefore, when unexpected noise is superimposed on the reference potential, the operation of the circuit becomes unstable. As described above, as a method for suppressing the fluctuation of the reference potential, it is known that a normal phase output and a reverse phase output are generated by an operational amplifier, and both are superimposed on the reference potential (for example, Patent Documents). 1).

  Further, a semiconductor integrated circuit device that can reduce crosstalk due to induction without disposing a large number of extra circuit elements has been disclosed (for example, see Patent Document 2). In the semiconductor integrated circuit device, the signal flow directions are mutually in part of the signal path such that the active path element such as an inverter that reverses the actual signal is not used and the signal path is folded in parallel and paralleled. A plurality of parallel wiring portions that are in opposite directions are formed. An inverter is not interposed in the middle of each parallel wiring portion, and that portion is a part of the actual wiring, and no extra circuit elements are required. When a signal is transmitted from one of the parallel wiring portions, the signal is turned back halfway, and the signal transmission direction is reversed. If the direction of the current flowing between the parallel conductors is reversed, the magnetic field in the opposite direction is canceled due to the electromagnetic property, and the generation of electromagnetic waves is suppressed. The parallel wiring portion can alleviate and further suppress crosstalk to other wiring in the vicinity.

JP-A-59-107615. JP 2003-158238 A.

  In recent electronic devices, such as cellular phones, which have been reduced in size and power consumption, the influence of even a very weak leak signal cannot be ignored. That is, in a small electronic device, since the mounting density on the internal substrate is high, the influence of a weak leak signal is relatively large as compared with a circuit mounted at a low density. Further, as the power consumption is reduced, the applied voltage of the DC voltage source is lowered and the reference potential with respect to the ground is also lowered, so that the influence of the weak leakage signal on the reference potential is relatively increased.

  In particular, in a wireless communication device such as a mobile phone, a transmission signal is amplified to an electric power necessary for wireless communication by an amplifier circuit in an extremely small casing, but the output signal of the amplifier circuit is the largest in the casing. There is a concern that the output signal is an interference signal for other devices and circuits when the output signal leaks to the power line circuit.

  In the above-mentioned Patent Document 1, fluctuations in the reference potential can be suppressed. However, in the recent electronic devices whose power consumption has been reduced because the reverse phase output of the operational amplifier is used to suppress the fluctuations. Is impossible to adopt. In addition, many components such as components for configuring operational amplifiers, components for adjusting the amplification factor, and output potential are required, and it is impossible to adopt them in recent electronic devices that are becoming smaller in size. It is.

  Further, assuming that the method of Patent Document 1 is applied, the inverting amplifier requires an inverting amplifier with high linearity that does not affect the signal amplified in the previous stage of the inverting amplifier, and is extremely weak. Adding to the circuit for the purpose of canceling the signal is impractical. Further, when attention is paid to a signal leaking to the power line circuit of the amplifier, in the above-mentioned Patent Document 1, a power line circuit is necessary for the inverting amplifier. The power line circuit of the amplifier becomes a noise source. As described above, the weak leakage signal cannot be suppressed as in the above-mentioned publication.

  The object of the present invention is to solve the above problems and to use a noise reduction circuit and method capable of reducing noise with a simple configuration without impairing downsizing and low power consumption, and the above-described noise reduction circuit. An object of the present invention is to provide a signal amplifier and a wireless communication apparatus.

A noise reduction circuit according to a first invention is
A signal amplifying unit that receives power supply from a power source via a power line circuit, amplifies an input signal, and outputs an output signal;
By acquiring and attenuating a part of the output signal from the signal amplifying means, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal Is added to the leaked signal to provide a signal adding means for substantially canceling the leaked signal.

  In the noise reduction circuit, the signal adding means is a passive circuit composed of a plurality of passive elements.

  Further, in the noise reduction circuit, the signal adding means uses a coupler composed of a pair of transmission lines arranged close to each other so as to be electromagnetically coupled to each other, and the cancellation signal is applied to the leakage signal. And adding.

Furthermore, in the noise reduction circuit, the power line circuit is
At the frequency of the leakage signal, a low impedance part that substantially short-circuits the leakage signal, and
A connection point between the low-impedance part and the signal amplifying means, and a high-impedance part that makes the connection point substantially open at the frequency of the leakage signal,
The signal adding means adds the leakage signal to the leakage signal at a position closer to the power source than the low impedance portion.

Here, the high impedance portion is a transmission line having a length of ¼ wavelength of the leakage signal,
The low impedance portion is a capacitor that allows a signal having a frequency of the leakage signal to pass therethrough.

  Furthermore, in the noise reduction circuit, the signal adding means is formed on a substrate on which the signal amplifying means is mounted.

A signal amplifier according to a second invention is a signal amplifier including the noise reduction circuit,
A power supply terminal connected to the power supply line circuit;
And an output terminal for outputting the output signal.

A wireless communication device according to a third invention is a wireless communication device including the noise reduction circuit,
A transmission means for transmitting the signal amplified by the signal amplification means is provided.

A wireless communication device according to a fourth aspect of the present invention is a wireless communication device comprising a receiving means for receiving a wireless signal having a predetermined frequency.
A noise reduction circuit according to claim 4 or 5,
The input signal is a square wave signal,
The power line circuit attenuates a leakage signal that is a part of the frequency component of the rectangular wave signal at a frequency of a radio signal used in the radio communication apparatus or an intermediate frequency or a frequency of a baseband signal related thereto. Features.

The noise reduction method according to the fourth invention is:
Receiving power from a power source via a power line circuit, amplifying an input signal and outputting an output signal;
By acquiring and attenuating a part of the output signal, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal is converted into the leakage signal. And substantially canceling out the leaked signal by adding together.

  According to the noise reduction circuit and method of the present invention, power is supplied from a power source through a power line circuit, an input signal is amplified and an output signal is output, and a part of the output signal is acquired and attenuated. To generate a canceling signal having substantially opposite phase and substantially the same amplitude as the leaking signal leaking into the power line circuit, and adding the canceling signal to the leaking signal, Substantially offset. As a result, noise can be significantly and effectively reduced with a simple configuration without impairing downsizing and low power consumption.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same component.

First embodiment.
FIG. 1 is a block diagram showing a configuration of a wireless communication circuit of a mobile phone according to the first embodiment of the present invention. FIG. 1 mainly shows a circuit related to transmission / reception of a radio signal. A mobile phone 10 includes an antenna 11, a circulator 12, a radio reception circuit 13, and a baseband signal processing circuit 14 for transmitting / receiving a radio signal. And a wireless transmission circuit 15. In the mobile phone 10, at the time of reception, a radio signal received via the antenna 11 is input to the radio reception circuit 13 via the circulator 13, and the radio reception circuit 13 performs a low frequency response to the received radio signal. Processing such as conversion and demodulation processing is executed, and the demodulated baseband signal is output to the baseband signal processing circuit 14. Based on the input demodulated signal, the baseband signal processing circuit 14 performs audio output, data processing, and the like.

The wireless transmission circuit 15 includes a modulation circuit 16, a driver circuit 17, and a noise reduction circuit 18, and these circuits 16, 17, and 18 are driven by a DC voltage Vcc of a DC voltage source. In the mobile phone 10, the baseband signal processed by the baseband signal processing circuit 14 is input to the wireless transmission circuit 15 during transmission. Modulation circuit 16 of the wireless transmission circuit 1 5 by modulating in accordance with the baseband signal input to a predetermined carrier signal, and generates a modulated radio signal, the driver circuit 17, the noise reduction circuit 18 and the circulator 12 The signal is output to the antenna 11 via the signal and transmitted from the antenna 11.

  As shown in FIG. 2, the noise reduction circuit 18 includes a transistor circuit 21 that functions as a power amplifier, and a cancellation signal addition circuit 25 that reduces noise. The latter cancellation signal addition circuit 25 is connected to the transistor circuit 21 from the transistor circuit 21. Acquire and attenuate part of the output signal. At this time, a cancellation signal having substantially opposite phase and substantially the same amplitude is generated for the output signal leaking to the power supply line circuit of the transistor circuit 21, and the cancellation signal is applied to the output signal leaking to the power supply line circuit. to add. Therefore, noise leaking from the noise reduction circuit 18 to the DC voltage source side can be suppressed.

  FIG. 2 is a block diagram showing a detailed configuration of the noise reduction circuit 18 of FIG. In FIG. 2, the noise reduction circuit 18 includes a transistor circuit 21, impedance matching circuits 22 and 23, a power supply line circuit 24, and a cancellation signal addition circuit 25. In this example, the power supply line circuit 24 includes a bypass capacitor 24a and a transmission line 24b. Further, the power supply line circuit 24 extends on the side opposite to the transistor circuit 21 as viewed from the bypass capacitor 24a, and is connected to the DC voltage source Vcc via the coupler 25b of the cancellation signal adding circuit 25.

  The transistor circuit 21 is an amplifier circuit that inputs and amplifies the radio signal output from the driver circuit 17, and the amplified transmission radio signal S becomes a transmission radio signal transmitted from the antenna 11. On the input side of the transistor circuit 21, an impedance matching circuit 22 is provided for suppressing the loss of the radio signal from the driver circuit 17 by matching the output impedance of the driver circuit 17 and the input impedance of the transistor circuit 21. On the output side of the transistor circuit 21, the output impedance of the transistor circuit 21 and the output impedance when the antenna 11 is viewed through the coupler 25a are matched to suppress the loss of the radio signal to be transmitted. An impedance matching circuit 23 is provided. The transistor circuit 21 and the impedance matching circuits 22 and 23 are configured to perform amplification and matching set in advance in the frequency band of the transmission radio signal S of the transistor circuit 21.

  Further, a power line circuit 24 is connected to the transistor circuit 21, and power is supplied to the transistor circuit 21 from the DC voltage source Vcc via the power line circuit 24. In the power line circuit 24, a transmission line 24b and a bypass capacitor 24a are connected between the transistor circuit 21 and the DC voltage source Vcc in order to suppress a leakage signal from the transistor circuit 21. Here, one end of the bypass capacitor 24a is connected to the output terminal of the transistor circuit 21, while the other end of the bypass capacitor 24a is connected to a ground conductor (for example, a ground conductor 111 in FIG. 9 described later). The signal in the frequency band of the transmission radio signal S is substantially short-circuited to the ground potential. Thereby, the bypass capacitor 24a forms a low impedance portion having a relatively low impedance with respect to the frequency band.

  The phase adjusting transmission line 24b is set between the bypass capacitor 24a and the transistor circuit 21 so as to be a 1/4 wavelength transmission line with respect to the signal in the frequency band of the transmission radio signal S. Yes. Therefore, the power supply line circuit 24 is substantially open with respect to the signal in the frequency band of the transmission radio signal S, and forms a high impedance portion having a relatively high impedance. For this reason, most of the transmission radio signal S of the transistor circuit 21 is transmitted to the impedance matching circuit 23, and a part thereof is transmitted to the power supply line circuit 24 side as the leakage signal N '.

  Although most of the leakage signal N ′ flows to the ground conductor due to the action of the bypass capacitor 24 a, a part of the leakage signal N ′ is transmitted to the DC voltage source Vcc by the power line circuit 24. Therefore, if no countermeasure is taken, an output signal (hereinafter referred to as a leakage signal N) leaking from the transmission line 24b to the DC voltage source Vcc side can be generated. However, in the mobile phone 10 as in the present embodiment, since miniaturization and low power consumption are progressing, even if the leakage signal N is weak, it cannot be ignored.

  Therefore, in the present embodiment, the canceling signal adding circuit 25 cancels the leakage signal N using a part of the transmission radio signal S as shown below. The cancellation signal adding circuit 25 is a passive circuit configured by including couplers 25a and 25b and a signal line 25c. In FIG. 2, the coupler 25a is configured to include a transmission line between the impedance matching circuit 23 and the antenna 11, and another transmission line disposed in close proximity so as to be electromagnetically coupled thereto. Then, a part of the transmission radio signal S output from the impedance matching circuit 23 is acquired and output to the coupler 25b via the signal line 25c.

  The coupler 25b includes a transmission line provided between the bypass capacitor 24a and the DC voltage source Vcc, and another transmission line disposed close to the electromagnetic wave so as to be electromagnetically coupled thereto. Composed. Here, with respect to the leakage signal N input from the power line circuit 24 to the coupler 25b, a part of the transmission radio signal S input from the coupler 25a to the coupler 25b via the signal line 25c is substantially omitted. The line length and characteristic impedance of the power supply line circuit 24 and the line length and characteristic impedance of the signal line 25c of the impedance matching circuit 23 and the cancellation signal adding circuit 25 are adjusted in advance so as to have the opposite phase and substantially the same amplitude. . Therefore, the coupler 25b of the cancellation signal adding circuit 25 adds a part of the transmission radio signal S acquired by the coupler 25a to the leakage signal N input from the power line circuit 24 to the coupler 25b. Thus, the leakage signal N is suppressed and is not transmitted to the DC voltage source Vcc side.

  In the present embodiment, since the signal of the signal source of the leakage signal N is the transmission wireless signal S, the frequency band of the transmission wireless signal S and the leakage signal N is the same band. Further, when the transmission radio signal S having a certain frequency is output, the frequency of the leakage signal N is substantially the same. Therefore, as in this embodiment, the canceling signal adding circuit 25, which is a passive circuit capable of adjusting the phase and amplitude, is configured to easily add a signal for canceling the leakage signal N to the power line circuit 24. Can do.

  Further, the transmission radio signal S is a signal after being amplified by the transistor circuit 21, and the leakage signal N is a signal obtained by further attenuating the leakage signal N ′ leaked to the power line circuit 24. Therefore, the power of the leakage signal N is extremely small compared to the power of the transmission radio signal S, and the cancellation signal for canceling the leakage signal N is generated by attenuating the power of the transmission radio signal S by the cancellation signal adding circuit 25. can do. For this reason, no new power consumption such as an amplifier circuit is required to cancel the leakage signal N, and this can be realized very simply by the passive circuit.

  In this embodiment, the transmission line connected to the signal line 25c in the coupler 25b is disposed close to the electromagnetic wave so as to be electromagnetically coupled to the transmission line between the bypass capacitor 24a and the DC voltage source Vcc. Therefore, the leakage signal N can be canceled without affecting the impedance when the power supply line circuit 24 is viewed from the output terminal of the transistor circuit 21.

  For example, when the transmission line of the coupler 25b is connected to the connection point between the bypass capacitor 24a and the transmission line 24b, the impedance of the transistor circuit 21 viewed from the power line circuit 24 side changes, and the transistor circuit 21 changes to the power line circuit 24. There is a possibility that the leakage signal N ′ leaking to the terminal increases. However, in the present embodiment, a coupler 25b is connected between the bypass capacitor 24a and the DC voltage source Vcc, and a power line circuit 24 including the bypass capacitor 24a and a transmission line 24b having a 1/4 wavelength line length. Thus, the leakage signal N can be further canceled while maintaining a mechanism for suppressing leakage of the leakage signal N to the power line circuit 24.

  Further, by connecting the coupler 25b between the bypass capacitor 24a and the DC voltage source Vcc, the cancellation signal adding circuit 25 can be coupled without considering the impedance when the transistor circuit 21 side is viewed from the bypass capacitor 24a. The configuration of the devices 25b, 25a, etc. can be determined. That is, in the canceling signal adding circuit 25, it is possible to determine the circuit configuration by paying attention only to the phase and amplitude of the leakage signal N, and the canceling signal adding circuit 25 can be designed with a very high degree of freedom. It is.

  As described above, the configuration that can be designed with a high degree of freedom is particularly important in the mobile phone 10 that is being miniaturized. That is, since the substrate and the like in the mobile phone 10 are small, it is not easy to change the arrangement and the like after determining components other than the cancellation signal adding circuit 25. However, if the design flexibility of the cancellation signal addition circuit 25 is high, it is easy to configure the cancellation signal addition circuit 25 without changing any components other than the cancellation signal addition circuit 25. Therefore, the present invention can be easily applied even to a small electronic device.

Second embodiment.
In the embodiment according to the present invention, it is only necessary to generate and add a signal that cancels noise by acquiring and attenuating a part of the transmission radio signal S after amplification. Also, various configurations can be adopted. FIG. 3 is a block diagram showing a detailed configuration of the noise reduction circuit 18a according to the second embodiment of the present invention. The noise reduction circuit 18a of FIG. 3 is characterized in that a cancellation signal addition circuit 26 is provided instead of the cancellation signal addition circuit 25 of FIG. 2 as compared with the noise reduction circuit 18 of FIG. In FIG. 3, the canceling signal adding circuit 26 includes a capacitor 27, couplers 26a and 26b, and a signal line 26c. That is, a configuration is adopted in which a part of the transmission radio signal S is acquired using a coupler 26 a including a transmission line to the transmission level detection circuit 70. Hereinafter, only the differences of FIG. 2 will be described in detail with respect to the configuration of FIG.

  In FIG. 3, the output terminal of the impedance matching circuit 23 is connected to the transmission level detection circuit 70 via the capacitor 27 and the coupler 26a, and a part of the transmission radio signal S output from the impedance matching circuit 23 is detected in the transmission level. The signal is supplied to the detector in the circuit 70 and used for detecting the level of the transmission radio signal S.

  Therefore, in the present embodiment, the cancellation signal adding circuit 26 is configured by a passive circuit. The coupler 26a of the canceling signal adding circuit 26 includes a transmission line between the capacitor 27 and the transmission level detection circuit 70, and a transmission line arranged in close proximity so as to be electromagnetically coupled thereto. The transmission line is connected to the coupler 26b via the signal line 26c. Therefore, a part of the transmission radio signal S transmitted from the capacitor 27 to the transmission level detection circuit 70 is acquired by the coupler 26a and then transmitted to the coupler 26b via the signal line 26c.

  Further, the coupler 26b of the cancellation signal adding circuit 26 includes a transmission line between the bypass capacitor 24a and the DC voltage source Vcc, and a transmission line arranged in close proximity so as to be electromagnetically coupled thereto. The coupler 26b cancels out the leaked signal N by adding a part of the transmission radio signal S acquired by the coupler 26a to the leaked signal N. That is, a part of the transmission radio signal S input from the coupler 26a to the coupler 26b via the signal line 26c is substantially opposite to the leakage signal N input from the power line circuit 24 to the coupler 26b. The line length and characteristic impedance of the power supply line circuit 24 and the line lengths and characteristic impedances of the impedance matching circuit 23, the coupler 26a, and the signal line 26c are adjusted in advance so that the phase and the amplitude are approximately the same. Therefore, the coupler 26b of the cancellation signal adding circuit 26 adds a part of the transmission radio signal S acquired by the coupler 26a to the leakage signal N input from the power line circuit 24 to the coupler 26b. Thus, the leakage signal N is suppressed and is not transmitted to the DC voltage source Vcc side.

  Also in the present embodiment, a canceling signal can be easily added to the leakage signal N by the canceling signal adding circuit 26 that is a passive circuit, as in the above-described embodiment. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit.

  Further, while maintaining a mechanism for suppressing the power that the transmission radio signal S leaks to the power supply line circuit 24 by the power supply line circuit 24 including the capacitor 24a and the quarter wavelength transmission line 24b, the power that further cancels the leakage signal N. Can be supplied. With this configuration, the cancellation signal adding circuit 26 can be designed with a very high degree of freedom. In addition, due to the high degree of design freedom of the cancellation signal addition circuit, it is possible to configure the cancellation signal addition circuit with various circuits, and various configurations shown in FIGS. 2 and 3 can be adopted. It becomes possible.

Third embodiment.
FIG. 4 is a block diagram showing a detailed configuration of a noise reduction circuit 18b according to the third embodiment of the present invention. The noise reduction circuit 18b of FIG. 4 is characterized in that it includes a cancellation signal addition circuit 28 instead of the cancellation signal addition circuit 25, as compared with the noise reduction circuit 18 of FIG. In the present embodiment, the cancellation signal adding circuit 28 includes transmission lines 28a, 28b, 28c, and 28d, the transmission lines 28c and 28b between the bypass capacitor 24a and the DC voltage source Vcc, and the impedance matching circuit 23. The attenuation and the phase of the transmission radio signal S are adjusted by changing the line length of the transmission lines 28a and 28d between the antenna 11 and the distance between the wires (preferably, further the characteristic impedance).

  In FIG. 4, the connection point between the transmission line 24b and the capacitor 24a is connected to the DC voltage source Vcc via the transmission line 28c and the transmission line 28b, while the output terminal of the impedance matching circuit 23 is connected to the transmission line 28d and the transmission line 28c. It is connected to the output terminal T2 to the antenna 11 through the line 28a. Here, the coupler 28A is configured to include a pair of transmission lines 28a and 28b that are arranged close to each other so as to be electromagnetically coupled to each other, and the attenuation amount of the transmission signal S mainly depending on the distance between the wires and the parallel length. Is adjusted. The transmission line 28c is a phase adjustment transmission line, and the line length and characteristic impedance of the transmission line 28c are adjusted so as to cancel each other. That is, in the present embodiment, the impedance matching circuit 23 is provided without using an independent circuit for acquiring a part of the transmission radio signal S using the transmission lines 28a and 28d between the impedance matching circuit 23 and the antenna 11. The canceling signal adding circuit 28 is configured together with the transmission lines 28b and 28c.

  In the cancellation signal adding circuit 28 configured as described above, the leakage signal N is canceled with a part of the transmission radio signal S and is not transmitted to the DC voltage source Vcc side. Similarly to the above-described embodiment, a signal that cancels the leakage signal N can be easily added to the transmission line 28b on the power line circuit 24 side by the passive circuit. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit. Furthermore, the power for canceling the leakage signal N using a part of the transmission radio signal S while maintaining a mechanism for suppressing the power of the leakage signal N that the transmission radio signal S leaks to the power supply line circuit 24 by the power supply line circuit 24. Can be supplied. With this configuration, the cancellation signal adding circuit 28 can be designed with a very high degree of freedom.

Fourth embodiment.
FIG. 5 is a block diagram showing a detailed configuration of a noise reduction circuit 18c according to the fourth embodiment of the present invention. The noise reduction circuit 18c of FIG. 5 is characterized in that a cancellation signal addition circuit 29 is provided in place of the cancellation signal addition circuit 25 of FIG. 1 as compared with the noise reduction circuit 18 of FIG. In the present embodiment, the canceling signal adding circuit 29 includes a coupler 29A including a pair of transmission lines 29a and 29c arranged close to each other so as to be electromagnetically coupled to each other, and a phase adjustment transmission line 29d. And a coupler 29B composed of a pair of transmission lines 29b and 29e arranged close to each other so as to be electromagnetically coupled to each other, and a transmission line between the bypass capacitor 24a and the DC voltage source Vcc. 29b, the transmission line 29a between the impedance matching circuit 23 and the antenna 11, and the line lengths of the transmission lines 29c, 29d, and 29e formed between them, and the inter-wiring distances (preferably more characteristic impedance) By adjusting, the attenuation and phase of the transmission radio signal S are adjusted.

  In FIG. 5, a part of the transmission radio signal S is acquired by the transmission line 29c of the coupler 29A, and the part of the signal is transmitted to the transmission line 29e of the coupler 29B via the phase adjustment transmission line 29d. By adjusting the phase and amplitude, the leakage signal N transmitted through the transmission line 29b connected to the power line circuit 24 is canceled by a part of the acquired transmission radio signal S, and the DC voltage source Vcc side Will not be transmitted.

  Also in this embodiment, a signal that easily cancels the leakage signal N by the passive circuit can be added to the leakage signal N flowing through the power line circuit 24, as in the above-described embodiment. Moreover, in order to cancel out the leakage signal N, new power consumption such as an amplifier circuit is not required, and can be realized very simply by a passive circuit. Furthermore, the power that cancels the leakage signal N while maintaining a mechanism that suppresses the power that the transmission radio signal S leaks to the power line circuit 24 by the power line circuit 24 that includes the bypass capacitor 24a and the quarter-wave transmission line 24b. Can be supplied. Further, with this configuration, the cancellation signal adding circuit 29 can be designed with a very high degree of freedom.

  FIG. 6 is a circuit diagram showing a detailed configuration of an example of the phase adjustment transmission lines 28c and 29d of FIG. For example, as shown in FIG. 6, the phase adjustment transmission lines 28c and 29d are L-type circuits including a capacitor C1 and an inductor L1, and include phase shift amounts by adjusting respective values of the capacitor C1 and the inductor L1. The line length, amplitude and characteristic impedance can be adjusted. The simulation results of the electrical characteristics of the phase adjustment transmission lines 28c and 29d will be described later in detail. Further, the transmission line 29d may be a series circuit of a capacitor C1 and an inductor L1, or a circuit including a resistor.

Application example to printed circuit board.
As described above, each embodiment according to the present invention can be realized by the various circuits as described above, and the cancellation signal adding circuit 26-29 is provided on the printed wiring board (dielectric board) 110 on which the signal amplifier IC 125 is mounted. It may be realized by the above, or may be realized inside the signal amplifier IC 125, and various modes can be adopted, which will be described in detail below.

FIG. 7 is a plan view showing a first application example when the noise reduction circuit 18 c of FIG. 4 is applied to the printed wiring board 1 10 . That is, FIG. 7 is a diagram illustrating the signal amplifier IC 125 mounted on the printed wiring board 110 and its peripheral circuits. In FIG. 7 , the signal amplifier IC 125 is connected to the power supply terminal 125a and the output terminal 125b. The strip conductors 121 and 122 on the printed wiring board 110 are shown. Here, the strip conductor 121 and the ground conductor 111 (see FIG. 9) formed on the back surface of the printed wiring board 110 constitute a microstrip line 121A, and the strip conductor 122 and the printed wiring board 110 are formed on the back surface. The ground strip 111 (see FIG. 9) constitutes a microstrip line 122A.

  The signal amplifier IC 125 shown in FIG. 7 is a circuit component that incorporates the impedance matching circuits 22 and 23 and the transistor circuit 21 in the noise reduction circuit 18 shown in FIG. 4, and the power supply terminal 125 a has the transistor circuit 21, the impedance matching circuit 23, and the like. The output terminal 125 b is connected to the output side of the impedance matching circuit 23. Therefore, in FIG. 7, the strip conductor 121 includes the transmission line 24 b of the power supply line circuit 24 in FIG. 4, and the strip conductor 122 corresponds to the line conductor between the antenna 11 and the impedance matching circuit 23. A bypass capacitor 24a is connected to a part of the strip conductor 121. The strip conductor 121 between the bypass capacitor 24a and the output terminal of the transistor circuit 21, the wiring conductor in the signal amplifier IC 125, and the power supply terminal 125a correspond to the transmission line 24b. To do. The other end of the bypass capacitor 24a is connected to the ground conductor 111 through a through-hole conductor 80 filled in a through-hole penetrating the printed wiring board 110 in the thickness direction and grounded. Therefore, in the first application example shown in FIG. 7, the strip conductor 122 connected to the output terminal 125 b is adjusted to the line length, shape, etc., and the part is electromagnetically coupled to the strip conductor 121. By arranging the coupler 28A in the vicinity, the leakage signal N transmitted on the strip conductor 121 by the coupler 28A is canceled by a part of the transmission radio signal S transmitted on the strip conductor 122. To do.

  According to the first application example configured as described above, in the printed wiring board 110 on which the arbitrary signal amplifier IC 125 is mounted, the leakage signal N leaking from the signal amplifier IC 125 to the power supply line circuit 24 cannot be ignored. Even if it exists, the said leak signal N can be canceled easily.

  FIG. 8 is a plan view showing a second application example when the noise reduction circuit 18c of FIG. 4 is applied to the signal amplifier IC125. As shown in FIG. 8, it is also possible to cancel the leakage signal N in the signal amplifier IC 125 so that noise does not leak from the signal amplifier IC 125. That is, the signal amplifier IC 125 includes a power supply terminal 125a and an output terminal 125b. The signal amplifier IC 125 includes the impedance matching circuits 22 and 23, the transistor circuit 21, the bypass capacitor 24a, and the transmission line shown in the noise reduction circuit 18 of FIG. Circuits corresponding to 24b and the cancellation signal adding circuit 25 are incorporated.

  On the semiconductor substrate of the signal amplifier IC 125 of FIG. 8, a strip conductor 123 including the transmission line 24b and the transmission line of the coupler 28A is formed between the transistor circuit 21 and the power supply terminal 125a, and the transistor circuit 21 and the output terminal 125b. The strip conductor 124 including the impedance matching circuit 23 and the transmission line of the coupler 28A is formed between the two. Here, the strip conductor 123 and a ground conductor (not shown, corresponding to the ground conductor 110 in FIG. 9) formed on the back surface of the semiconductor substrate 110 </ b> A constitute a microstrip line 123 </ b> A, The microstrip line 124A is constituted by a ground conductor (not shown, corresponding to the ground conductor 110 in FIG. 9 and the like) formed on the back surface of the semiconductor substrate 110A. One end of the bypass capacitor 24a is connected to a part of the strip conductor 123, and the other end is connected to the ground conductor via a through-hole conductor 80 filled in a through-hole penetrating the semiconductor substrate 110A in the thickness direction. Grounded. The impedance matching circuit 23 includes a part of the strip conductor 124 and capacitors 126 and 127 each having one end grounded via the through-hole conductor 80. Here, the cancellation signal addition is performed by the impedance matching circuit 23, the strip conductor 124, the strip conductor 123, and the coupler 28A that is disposed close to each other so that the two strip conductors 123 and 124 are electromagnetically coupled to each other. A circuit 28 is configured.

  In FIG. 8, the impedance matching circuit 22 is not shown. Here, by adjusting the line length, shape, and the like of the strip conductor 124, the leakage signal N is substantially canceled by adding a part of the transmission radio signal S to the leakage signal N by the coupler 28A. According to the above configuration, the leakage signal N can be prevented from leaking to the external circuit from the power supply terminal 125a of the signal amplifier IC125.

  Further, the noise reduction circuit according to the present invention may be configured by elements different from the circuit elements described in the above embodiments. For example, although the transmission line 24b described above may be configured by the strip conductors 121 and 122, the frequency of the transmission radio signal S can be increased by connecting a circuit including a choke coil and a bypass capacitor to the output terminal of the transistor circuit 21. Alternatively, a circuit having a high impedance may be configured. Further, the passive circuit described above can be constituted by various circuit elements other than the wiring pattern such as the strip conductors 121-124, and a combination of various elements such as a coil, a capacitor, and a resistor can be adopted.

  7 and 8, the signal amplifier IC 125 is used. However, the present invention is not limited to this. The signal amplifier is not formed in the IC, and the signal amplifier is configured using a field effect transistor. May be.

  Further, in the above-described example, the power line circuit 24 and the cancellation signal adding circuit 25 are described in the same layer on the printed wiring board 110 or the semiconductor substrate 110A. However, these circuits are formed in different layers. May be. That is, the canceling signal adding circuit 25 can transmit power from the strip conductor 121 or 123 between the impedance matching circuit 23 and the antenna 11 to the wiring such as the strip conductor between the bypass capacitor 24a and the DC voltage source Vcc. As long as possible, the power supply line circuit 24 and the cancellation signal adding circuit 25 may be formed in different layers, and various configurations can be employed. Of course, any one or both of the power supply line circuit 24 and the cancellation signal adding circuit 25 may be formed in a plurality of layers via the through-hole conductor 80. In particular, an embodiment of the coupler 28A will be described in detail below.

FIG. 9 is a longitudinal sectional view showing the embodiment of FIG. 7 when the coupler 28A of FIG. 4 is applied to the printed wiring board 1 10 . In FIG. 9, the strip conductors 28as and 28bs of a pair of transmission lines of the coupler 28A are juxtaposed in close proximity to each other on a printed wiring board 110 having a ground conductor 111 formed on the back surface. Has been. The coupler 28A is configured by the above configuration.

FIG. 10 is a longitudinal sectional view showing a first modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 1 10 . In FIG. 10, a pair of transmission line strip conductors 28as and 28bs of a coupler 28A are formed close to each other on a printed wiring board 110 having a ground conductor 111 formed on the back surface thereof. However, the strip conductor 28as is formed on the front surface of the printed wiring board 110, the dielectric layer 112 is formed thereon, and the strip conductor 28bs is formed on the strip conductor 28as immediately above the strip conductor 28as. . The coupler 28A is configured by the above configuration.

FIG. 11 is a longitudinal sectional view showing a second modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 1 10 . In the second modified example of FIG. 11, the strip conductor 28bs is formed on the dielectric layer 112 at a position shifted from the position immediately above the strip conductor 28as, as compared with the first modified example of FIG. The coupler 28A is configured by the above configuration.

FIG. 12 is a longitudinal sectional view showing a third modification when the coupler 28A of FIG. 4 is applied to the printed wiring board 1 10 . The third modification of FIG. 12 is formed so that the pair of strip conductors 28as and 28bs of the coupler 28A are orthogonal to each other as compared with the first modification of FIG. The coupler 28A is configured by the above configuration.

  Although the two-layer structure is shown in the examples of FIGS. 9 to 12, the present invention is not limited to this, and the structure may be formed of strip conductors 28as and 28bs in arbitrary layers with a structure of three or more layers. Further, the pair of strip conductors 28as and 28bs need not be parallel to each other and may not have the same line width.

  Further, the case where the input signal to the noise reduction circuit 18 in FIG. 2 is a rectangular clock signal will be discussed below. 13 is a diagram showing a time waveform of a rectangular clock signal that is an input signal of the noise reduction circuit 18 of FIG. 2, and FIG. 14 is a diagram showing frequency characteristics of frequency components of the rectangular clock signal of FIG. is there. When the input signal to the noise reduction circuit 18 of FIG. 2 is a rectangular wave clock signal as shown in FIG. 13, the clock signal includes a harmonic component and has a relatively wide frequency band as shown in FIG. In the place where the frequency band of the communication system and the harmonic component of the clock signal overlap with each other, the frequency band of the radio signal and the low frequency are compared with the circuit of the communication system (particularly the receiving circuit). In the frequency band related to the frequency band of the radio signal, such as the frequency band of the intermediate frequency signal after conversion and the frequency band of the baseband signal, there is a possibility that an influence such as interference may occur. In particular, when the reception frequency band and the harmonic component of the clock signal overlap, a minute received signal power cannot be restored correctly, and for example, a mobile phone cannot be used for communication. When a clock signal is amplified, all harmonic components leak to the bias circuit side. However, by using the noise reduction circuits 18, 18a, 18b, and 18c according to the present embodiment, only the frequency band that affects the communication system is used. (Because the power supply line circuit 24 operates as a filter circuit that removes only a predetermined frequency band or passes only another predetermined frequency band as described above), the leakage signal N can be significantly reduced. It has the following effects. In this case, for example, the transistor circuit 21 is a circuit such as a mixer provided in the wireless reception circuit 13 of the wireless communication device. Further, the application example described with reference to FIGS. 13 and 1 as described above can be applied to, for example, a digital circuit.

FIG. 15 is a circuit diagram of a simulation circuit substantially corresponding to the noise reduction circuit 18c of FIG. 5 used in the simulation by the present inventors. In FIG. 15, the simulation circuit is realized by a harmonic balance analysis method using a simulator ADS (Advanced Design System) manufactured by Agilent, and includes a reference high-frequency signal generator 30 including an internal output resistance Rr, a transmission line, and the like. 31-38, 39a, 39b, 40-43, field effect transistors TR1, TR2, resistors R11, R21, capacitors C11-C13, C21, inductors L11, L21, DC voltage sources 51, 52, a load And a resistor _RL . Here, a pair of transmission lines 39a and 39b constitutes a coupler 39, and a transmission line 38, a capacitor C13, and a coupler 39 constitute a cancellation signal adding circuit 60. In the simulation circuit configured as described above, the voltage waveform of the bias voltage was measured at the monitor point Tm that is the connection point of the transmission lines 42 and 43.

  FIG. 16 is a waveform diagram showing the simulation result of FIG. 15 and showing the time waveform of the bias voltage when the noise reduction circuit 60 for confirming the noise reduction effect is present. As can be seen from FIG. 16, when the noise reduction circuit 60 is not provided, the leakage signal N is superimposed on the bias voltage. However, when the noise reduction circuit 60 is provided, the leakage signal N is significantly reduced. I understand that.

  17 is a graph showing the frequency characteristics of the relative power of the pass coefficient in the phase adjustment transmission line of FIG. 6, and FIG. 18 is a graph showing the frequency characteristics of the phase of the pass coefficient in the phase adjustment transmission line of FIG. . As apparent from FIGS. 17 and 18, it is understood that the passing power can be changed according to the frequency and the phase shift amount can be changed.

Summary of embodiments of the present invention.
According to the present invention, when the output signal amplified by the signal amplifying means leaks to the power supply line circuit, a part of the output signal is attenuated, and has substantially the same phase and the same amplitude as the leaked output signal. Noise is suppressed by adding signals. That is, the noise to be suppressed is a signal in which the output signal amplified by the signal amplifier leaks to the power supply line circuit, and is a weak signal. On the other hand, the signal generated by the signal adding unit is generated from a part of the output signal after being amplified by the signal amplifying unit, and the amplified output signal is a signal having a large power.

  Therefore, the signal adding means in the present invention does not require an amplifier circuit in order to generate the signal having the substantially opposite phase and substantially the same amplitude, and can be generated by attenuating the output signal. As a result, it is possible to provide a circuit that cancels out the output signal leaking to the power line circuit without power consumption. In addition, when generating the signal having substantially the same phase and amplitude, the components for forming the amplifier circuit and the like are completely unnecessary, and the signal adding means can be realized without hindering the miniaturization of the circuit. it can.

  Here, the signal amplifying means may be any circuit that amplifies the input signal and obtains the output signal, and amplifies the input signal using the power supplied via the power line circuit. Of course, it is possible to appropriately perform impedance matching or insert a filter in each line connected to the signal amplification means.

  In the present invention, when an input signal is amplified to obtain an output signal, a signal leaking to the power line circuit is suppressed. Therefore, if a signal amplifying means that causes a signal to leak into the power supply line circuit is used as an application object of the present invention, the effect appears remarkably, and amplifying means for a high-frequency signal (for example, a signal of 30 MHz or more) An example. For this reason, the present mobile phone using the 800 MHz to 2 GHz band, the current wireless LAN using the 2 GHz and 5 GHz bands, and the like are suitable applications of the present invention.

  The signal adding means acquires a part of the output signal from the signal amplifying means. That is, in the present invention, the output signal leaked from the signal amplification means is canceled using the output signal amplified by the signal amplification means. In the signal amplification means, the former is an output signal to be acquired by amplification, and the latter is not required. In general, the former is much larger than the latter because of the noise. Therefore, in the signal adding means, it is possible to obtain a signal that can sufficiently cancel out the leaked signal only by obtaining a part of the output signal from the signal amplifying means.

  In addition, various configurations can be employed to acquire a part of the output signal, and a wiring that conducts with the wiring that transmits the output signal is not essential. That is, if the output signal is a high-frequency signal, a circuit that becomes part of the signal adding means is wired near the transmission line through which the output signal is transmitted. To leak. Therefore, a configuration may be adopted in which a part of the output signal is acquired by wiring that is not secured to the output line of the signal amplification means. According to this configuration, it is possible to generate a signal that cancels out the output signal leaking to the power supply line circuit without excessively damaging the output power of the signal amplification means.

Further, the signal adding means only needs to be able to attenuate the output signal from the signal amplifying means, and may be configured to attenuate the signal simultaneously by acquiring a part of the output signal as described above. Then, a configuration in which a part of the output signal is acquired and the signal whose power is attenuated is further attenuated may be used. Since such signal attenuation can be performed without receiving power from the power source, the attenuation can be realized with a very simple configuration.

  Further, the signal generated by the signal adding means may be a signal having substantially the same phase and amplitude as the output signal leaking to the power line circuit. That is, it is only necessary to generate a signal that cancels the output signal leaking to the power line circuit. Of course, if the output signal leaks to the power supply line circuit is exactly the opposite phase and the same amplitude, the leaking signal can be canceled out. However, if it is difficult to accurately specify the phase and amplitude of the leaking signal, it is sufficient that the signal adding means adds the signals and attenuates at least the leaking signal.

  In this sense, it is only necessary that the signal adding means can generate a signal having substantially the same phase and amplitude as the output signal leaking to the power supply line circuit. For example, a configuration may be adopted in which a signal having substantially opposite phase and substantially the same amplitude as the output signal leaking to the power supply line circuit is generated by a wiring or component that can be actually selected.

  Further, since the output signal may have a predetermined frequency band, the signal adding means has a signal having the largest amplitude in the frequency band in the output signal leaking to the power line circuit, and having the highest transmission efficiency. A configuration may be adopted in which a signal having a frequency that is most desired to be suppressed, such as a large signal, is selected, and a signal having substantially the same phase and amplitude is added to this signal.

  In the present invention, the output signal leaking to the power line circuit is a part of the signal amplified by the signal amplifying means and substantially coincides with the frequency band of the amplified signal. Therefore, by canceling the output signal leaking to the power line circuit by a part of the amplified signal, it is possible to attenuate the leak signal for all frequency bands of the output signal leaking to the power line circuit very easily. is there.

  Furthermore, the signal adding means in the present invention may be constituted by a passive circuit. That is, the passive circuit is a component of a circuit that does not have an amplifying function, such as a resistor, a capacitor, and a coil. These components transmit the signal while giving attenuation and phase fluctuation to the signal. In the present invention, a signal that attenuates a part of the output signal having a large power and leaks to the power line circuit. Therefore, this signal can be easily generated by a passive circuit. Further, since it is a passive circuit, it is not necessary to supply power from the power source when generating this signal. Furthermore, since the signal adding means can be realized by simple components, the device can be easily downsized.

  As described above, as an example of configuring the signal addition unit with a passive circuit, an example of configuring the signal addition unit with only wiring may be employed. That is, it is possible to adjust the phase and amplitude of the output signal by adjusting the length and shape of the wiring, the distance between the closely arranged wirings, the parallel wiring length, and the like. It is possible to obtain a part of the output signal from the signal and add it to the power line circuit to cancel the leaked output signal. According to this configuration, the signal adding means can be formed very easily.

  Note that the present invention may be applied to signal amplifying means adopting a configuration for suppressing an output signal leaking into the power line circuit. That is, in the power line circuit, leakage of the output signal can be suppressed by adjusting the impedance with respect to the frequency of the output signal. For example, in the power line circuit, a low impedance part whose ground is substantially short-circuited at the frequency of the leaked output signal, and a power line circuit between the low impedance part and the signal amplification means A high impedance portion that is substantially open to the frequency is formed.

  According to this configuration, an output signal leaking to the power supply line circuit can be suppressed by the high impedance portion and the low impedance portion. However, even if such a circuit is configured with actual circuit components, the leaked output signal cannot be completely set to “0”, and a part of the power leaks to the power source side. Such a leakage cannot be ignored in recent electronic devices whose size and power consumption have been reduced.

  Therefore, if the present invention is applied to the configuration in which the leakage of the output signal is suppressed by the impedance as described above in the power line circuit, the leakage of the output signal to the power line circuit can be suppressed to an extremely small level. At this time, the signal generated by the signal adding means is added to the power supply side from the low impedance portion. That is, in the power line circuit, since the leakage of the signal is prevented by the combination of the low impedance part and the high impedance part, if the signal by the signal adding means is added to the power source side from the low impedance part, the low impedance part The signal leaking from the low impedance part to the power supply side can be further suppressed while maintaining a mechanism for preventing the signal leakage by combining the low impedance part and the high impedance part.

  Note that the low impedance portion and the high impedance portion may be configured to suppress signals leaking to the power supply line circuit when they are combined. However, even if these low-impedance part and high-impedance part are configured by actual circuit components or the like, the impedance by the low-impedance part cannot be “0” and the impedance by the high-impedance part cannot be made infinite. In this sense, in the low impedance part, the signal at the frequency of the output signal is substantially short-circuited to the ground, and in the high impedance part, the signal is leaked by being substantially open to the signal at the frequency of the leaking output signal. It is sufficient if the signal can be suppressed.

  As such a configuration, for example, a low-impedance part is configured by a capacitor that passes a signal having a frequency of the leaking output signal, and the leakage signal between the low-impedance part and the signal amplification means is 1 / of the leaking output signal. The high impedance portion can be formed by a transmission line having a length of 4 wavelengths. According to this configuration, the low impedance portion and the high impedance portion can be configured by a very simple circuit.

  As described above, the signal adding means adds signals while maintaining a mechanism for preventing signal leakage by combining the low impedance portion and the high impedance portion, thereby greatly increasing the degree of design freedom in the signal adding means. can do. That is, when adopting a configuration in which a signal is added to the power line circuit of the signal amplifying unit, the impedance of the power line circuit as viewed from the signal amplifying unit generally fluctuates. Need to design.

  However, as described above, if the signal generated by the signal adding means is added to the power supply side from the low impedance portion, the power amplification side from the low impedance portion that is substantially short-circuited to the ground when viewed from the signal amplification means. Since the addition by the signal adding means is performed, the impedance viewed from the signal amplifying means hardly changes. Therefore, as long as a signal is added to the power supply side from the low impedance part, the circuit configuration in the signal adding means can be freely determined, and a design with a very high degree of freedom can be performed.

  Furthermore, although the ground is substantially short-circuited at the frequency of the leaked output signal by the low impedance unit, the signal added by the signal adding means is obtained by acquiring and attenuating a part of the output signal. Even at the frequency of the signal to be added, the ground is substantially short-circuited by the low impedance portion. Therefore, it is possible to cancel the signal without leaking the signal added by the signal adding means to the signal amplifying means side.

  Furthermore, the noise reduction device according to the present invention can be applied to various signal amplification means. For example, if the signal amplifying means is provided as one component and the component is mounted on the substrate, the signal leaking from the component can be suppressed by forming the signal adding means for the substrate. . Therefore, even when a component that leaks noise is used, the noise can be easily suppressed.

  Furthermore, it is also possible to provide a component that does not leak noise according to the present invention. As an example for that purpose, a component including a signal amplifying unit and a signal adding unit according to the present invention, and a power terminal connected to the power line circuit and an output terminal for outputting the output signal may be configured. . That is, the output signal leaking to the power line circuit is canceled inside the component, and the output signal does not leak from the power terminal. Therefore, the user of this component can supply predetermined power from the power supply terminal without considering the leakage signal and obtain an output signal from the output terminal.

  Furthermore, as an example of an application target of the present invention, a wireless communication device such as a mobile communication device can be employed. That is, in a mobile communication device, a transmission signal is obtained by a signal amplifying means, and the transmission signal often becomes large power in this device. In recent years, mobile communication devices have been reduced in size and power consumption, and there are cases where the influence of the output signal amplified by the signal amplification means cannot be ignored. Therefore, if a mobile communication device including the signal amplification means and the signal addition means of the present invention is configured, it is possible to provide a mobile communication device with a small size and low power consumption without being affected by noise.

  Although the case where the present invention is realized as an apparatus has been described above, the present invention can also be applied to a method for realizing such an apparatus. Of course, the substantial operation is the same as that of the apparatus described above. In addition, the noise reduction apparatus as described above may be realized alone, applied to a certain method, or used in a state where the method is incorporated in another device. However, the present invention is not limited to this and includes various modes.

  As described in detail above, according to the noise reduction circuit and method of the present invention, power is supplied from a power supply via a power supply line circuit, an input signal is amplified and an output signal is output, and the output signal By acquiring a part and attenuating, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal is added to the leakage signal. This substantially cancels the leakage signal. As a result, noise can be significantly and effectively reduced with a simple configuration without impairing downsizing and low power consumption. Therefore, the present invention can be widely applied to wireless communication devices such as mobile phones and GPS receivers.

It is a block diagram which shows the structure of the radio | wireless communication circuit of the mobile telephone which concerns on the 1st Embodiment of this invention. FIG. 2 is a block diagram showing a detailed configuration of a noise reduction circuit 18 in FIG. 1. It is a block diagram which shows the detailed structure of the noise reduction circuit 18a which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the detailed structure of the noise reduction circuit 18b which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the detailed structure of the noise reduction circuit 18c which concerns on the 4th Embodiment of this invention. FIG. 5 is a circuit diagram illustrating a detailed configuration of an example of the phase adjustment transmission lines 28c and 29d in FIG. 4. 5 is a plan view showing a first application example when the noise reduction circuit 18c of FIG. 4 is applied to a printed wiring board 1 10; FIG. 6 is a plan view showing a second application example when the noise reduction circuit 18c of FIG. 4 is applied to a signal amplifier integrated circuit (hereinafter referred to as a signal amplifier IC) 125. FIG. FIG. 8 is a longitudinal sectional view showing the embodiment of FIG. 7 when the coupler 28 </ b> A of FIG. 4 is applied to a printed wiring board 1 10 . FIG. 6 is a longitudinal sectional view showing a first modification when the coupler 28 </ b> A of FIG. 4 is applied to the printed wiring board 1 10 . FIG. 6 is a longitudinal sectional view showing a second modification when the coupler 28 </ b> A of FIG. 4 is applied to the printed wiring board 1 10 . FIG. 10 is a longitudinal sectional view showing a third modification when the coupler 28 </ b> A of FIG. 4 is applied to the printed wiring board 1 10 . FIG. 3 is a diagram illustrating a time waveform of a rectangular-wave clock signal that is an input signal of the noise reduction circuit 18 of FIG. 2. It is a figure which shows the frequency characteristic of the frequency component of the clock signal of the rectangular wave of FIG. 6 is a circuit diagram of a simulation circuit substantially corresponding to the noise reduction circuit 18c of FIG. 5 used in the simulation by the present inventors. FIG. FIG. 16 is a waveform diagram showing the time waveform of the bias voltage when the presence or absence of a noise reduction circuit for confirming the noise reduction effect is shown in the simulation result of FIG. It is a graph which shows the frequency characteristic of the relative electric power of the passage coefficient in the transmission lines for phase adjustment 28c and 29d of FIG. It is a graph which shows the frequency characteristic of the phase of the passage coefficient in the transmission lines for phase adjustment 28c and 29d of FIG.

Explanation of symbols

10 ... mobile phone,
11 ... Antenna,
12 ... circulator,
13: Wireless receiver circuit,
14 ... baseband signal processing circuit 15 ... wireless transmission circuit,
16 ... modulation circuit,
17 ... driver circuit,
18 ... Noise reduction circuit,
21 ... transistor circuit,
22, 23 ... impedance matching circuit,
24 ... Power line circuit 24a ... Bypass capacitor,
24b ... transmission line,
25, 26 ... canceling signal adding circuit,
25a, 25b, 26a, 26b ... couplers,
25c, 26c ... signal lines,
27. Capacitor,
28, 29 ... canceling signal adding circuit,
28A, 29A, 29B ... couplers,
28a, 28b, 28c, 28d, 29a, 29b, 29c, 29d, 29e ... transmission line,
28as, 28bs ... strip conductors,
70: Transmission level detection circuit,
80 ... through-hole conductor,
110 ... printed wiring board,
110A ... Semiconductor substrate,
111 ... Grounding conductor,
112 ... dielectric layer,
121, 122, 123, 124 ... strip conductors,
121A, 122A, 123A, 124A ... microstrip line,
125... Signal amplifier IC,
125a ... power supply terminal,
125b ... signal output terminal,
126, 127: capacitors.

Claims (10)

A signal amplifying unit that receives power supply from a power source via a power line circuit, amplifies an input signal, and outputs an output signal;
By acquiring and attenuating a part of the output signal from the signal amplifying means, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal A noise reduction circuit comprising: signal adding means for substantially canceling out the leaked signal by adding to the leaked signal.   2. The noise reduction circuit according to claim 1, wherein the signal adding means is a passive circuit comprising a plurality of passive elements.   The signal adding means adds the canceling signal to the leakage signal using a coupler comprising a pair of transmission lines arranged close to each other so as to be electromagnetically coupled to each other. The noise reduction circuit according to claim 1 or 2, wherein The power line circuit is
At the frequency of the leakage signal, a low impedance part that substantially short-circuits the leakage signal, and
A connection point between the low-impedance part and the signal amplifying means, and a high-impedance part that makes the connection point substantially open at the frequency of the leakage signal,
The said signal addition means adds the said leak signal with respect to the said leak signal in the position of the said power supply side from the said low impedance part, The one of Claim 1 thru | or 3 characterized by the above-mentioned. Noise reduction circuit. The high impedance part is a transmission line having a length of ¼ wavelength of the leakage signal,
5. The noise reduction circuit according to claim 4, wherein the low impedance part is a capacitor that allows a signal having a frequency of the leakage signal to pass therethrough.   The noise reduction circuit according to claim 1, wherein the signal adding unit is formed on a substrate on which the signal amplifying unit is mounted. A signal amplifier comprising the noise reduction circuit according to any one of claims 1 to 6,
A power supply terminal connected to the power supply line circuit;
A signal amplifier comprising: an output terminal for outputting the output signal. A wireless communication device comprising the noise reduction circuit according to any one of claims 1 to 6,
A wireless communication apparatus comprising: a transmission unit that transmits a signal amplified by the signal amplification unit. In a wireless communication apparatus provided with a receiving means for receiving a wireless signal having a predetermined frequency,
A noise reduction circuit according to claim 4 or 5,
The input signal is a square wave signal,
The power line circuit attenuates a leakage signal that is a part of the frequency component of the rectangular wave signal at a frequency of a radio signal used in the radio communication apparatus or an intermediate frequency or a frequency of a baseband signal related thereto. A wireless communication device. Receiving power from a power source via a power line circuit, amplifying an input signal and outputting an output signal;
By acquiring and attenuating a part of the output signal, a cancellation signal having substantially the same phase and amplitude as the leakage signal leaking to the power line circuit is generated, and the cancellation signal is converted into the leakage signal. And substantially canceling out the leakage signal by adding to the noise reduction method.

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